I'm going to start by saying that I don't like the Mamono. Personally, I don't think APCs and IFVs have any business being slow and heavy, which typically also results in expensive. I would have much preferred a lightweight OmniVehicle instead, but the design requirements for what became the Mamono dictated that it be a 70 ton "heavy IFV". Bleh.
Taking its inspiration from images of USMC AAV7s involved in urban combat, the Mamono is an odd DUKW. On the one hand, its slowish speed and the range of its armament is perhaps best suited to the confines of city fighting. But on the other hand, its limited amphibious capability is what you'd expect from a vehicle that operates out in the wild, perhaps far from such civilized inventions as bridges and ferries. Maybe the DCMS intends to invade Venice?
Sadly, I can't recall the armament for my original design proposal for the Mamono, with that iteration deemed not Kuritan enough. The next version lacked only the Apollo FCS, carrying extra LMGs instead, with last addition leaving the design groaning under the weight of signature Kuritan technology, including some of their latest bells and whistles. Unfortunately, that fancified technology helps rack up the price of what is an expensive battle taxi, equivalent in cost to around five Maxim Mk IIs in C-Bill terms.
At the core of the Mamono and its impressive price tag is an XL engine. Not too long ago, the idea of a XL-engined vehicle would have resulted in you running for your life from a mob of jeering players, but thanks to Technical Readout 3145 Draconis Combine and its ilk, they're now ten a penny. Of course, the Experimental series and Technical Readout Prototypes had already opened that particular Pandora's Box, but 3145 ensured that it wasn't just a passing fad.
Able to keep up with most heavy ’Mechs and tanks, the Mamono isn't going to be your first choice for rapidly deploying troops, but neither is it unmanageably slow. The Mamono could have perhaps been made faster, but personally I feel that would both be too little gain for too much cost and would have also made it too similar in concept to the Magi (UCSV). Making it slower simply wasn't an option, as it was already at its minimum acceptable speed in my eyes.
So apart from passable speed, what does the Mamono get for such an extravagant powerplant? For a start, it saves twelve tons, which allows it to have both thick armor and a heavy weapon payload in addition to its cargo of infantry. Could the Mamono have been built to a lesser standard by using a standard engine instead? Obviously it could, but I already think such a heavy IFV is a bad idea and so if you're gonna be dumb you gotta be tough.
Protecting the Mamono is an impressive 10 tons of Reflective armor, which is one of the flavors of the month for the Kuritans. While it's a decent choice for battle armor such as the Zou or ASFs like the Koroshiya, I'm not convinced it's a good options for ’Mechs and vehicles. Especially a vehicle with an urban combat focus, with the increased vulnerability from collapsing buildings or meeting Hatchetmen down dark alleys or having to assault a city protected by Destriers.
Still, putting such flaws aside, the Mamono is a tough nut to crack, able to suffer a pair of Gauss Rifle strikes to any facing without being penetrated, apart from the front, which is even stronger. Added to the raw strength of the armor, the AMS perched atop the turret will hopefully reduce the chance of a mobility kill due to missile swarms. With the CASE providing the cherry on top, the Mamono can at least bully its way through heavy fire to deliver its infantry.
As you'd expect of a Kuritan design, the Mamono isn't just going to sit there and take abuse, and it's perfectly capable of dishing it out itself. The Apollo-enhanced MRM40 and the coax Snub-nose PPC are only able to reach out to fifteen hexes, which is uncomfortably short ranged for a vehicle unable to dictate the distance the fight will occur. However, inside those fifteen hexes, the Mamono's missiles and PPC can inflict an average of 34 damage per Turn, which is a massive threat to any foe.
That firepower does create a large bubble that the enemy should avoid, which will prevent closer and thus more accurate engagement of the infantry when they're embarking and debarking. Really, the MRM40 alone is capable of that, and twin Light PPCs would have provided a viable alternative to the Snub PPC, but even then that would have only extended the reach by three hexes. The best solution is to partner the Mamono with something that has the ER PPCs, Gauss Rifles, LRMs, etc to be able to provide long range covering fire.
Appearing almost as an afterthought, the side-mounted LMGs are what remains of the four guns that once covered every arc, one apiece. As noted above, jymset wanted the Mamono to mount the Apollo, which meant that two of the guns had to go. Some would have no doubt preferred a fore/aft configuration, or perhaps one in the turret and the other forward or rearward facing, but the Mamono got its LMGs on its flanks because reasons. Seriously, it was just a spur of the moment choice with little thought. Sorry.
As noted above, the inspiration provided by the AAV7 was the main motivator for adding the Limited Amphibious Equipment. As also noted above, it's not something that sits well with an urban combatant. Of course, even a streetfighter still has to get to the city, and the Mamono's swimming capability does mean that it doesn't need to wait around for a bridgelayer if an inconvenient river gets in the way, nor are defenders of ports free to view the shore as a protected flank. The Mamono might be slow as it paddles through the water, but that's more than can be said for most wheeled and tracked vehicles, which would just have to wait forlornly as the Mamonos go off to win all the glory.
Finally, we get to the key feature of the Mamono: its infantry compartment. This was deliberately scaled to be large enough to carry a squad of assault-class battlesuits for those that prefer to use the optional battle armor transportation rules, but if you use the default rules the Mamono can carry a pair of squads. Instead of one or both battle armor squads, you could opt to carry a foot or jump infantry platoon. A single mechanized infantry platoon in lieu of any other troops would also be possible, but personally I'd view that as the weakest choice compared to the possibility of dual squads/platoons or a combination thereof.
I like my footsloggers, so I tend to view them as the primary arm of the vehicle/infantry combo, but obviously your mileage may vary. Even though I may grumble about the excesses of such a large IFV, at least the Mamono does deliver plenty of infantry and/or battle armor. The flexibility of the large bay is no small advantage, whether you use it to mix and match or to simply double up. Expensive though it may be, the Mamono can also afford to stick around in the fight once its infantry payload engages, keeping the enemy under pressure to potentially allow the little guys more freedom to maneuver.
Although the Mamono has yet to spawn any variants, the large infantry bay would be conducive to simple modifications, such as installing Communications Equipment or a Master C3. With the majority of the weapon mass in the turret, that would also present the possibility of a turret swap for a new armament, ideally one that addresses the range issue.
Like so many other relatively slow designs with a well-defined mission focus, using the Mamono is fairly simple: just point it towards where you want to deploy the infantry and don't stop until you get there, blasting all obstacles in your way. OK, I'm being flippant there, but that pretty much is it. Unlike lightweights such as the Suns' JI2A1, you don't have to carefully thread your way past the enemy to get your infantry through.
Personally, even with the ability to fight through stiff opposition and deploy under fire, I'd still rather go for smaller, quicker vehicles. With those, you always have the ability to get to a battlefield that a Mamono simply can't reach in time; perhaps even getting to deliver your infantry before the enemy even arrives, and then go back for more. If I need to drop my troops in the teeth of the enemy, then I'd really rather use OmniMechs to carry medium and heavy battle armor to the fight, as there's typically less chance of a mobility kill before the carrier gets to the drop off point. In situations where there's little risk of the APC/IFV being hit and stranded before it unloads the troops, such as very dense urban areas, then you could simply drop off the infantry further away and let them walk into position, equally safe from incoming fire.
Overall, I feel the Mamono is just too much metal to achieve its goal. If a slow, heavily armored vehicle was still demanded, then it should be no more than 50 tons, so that you can take advantage of light vehicle bays, and thus carry more of them on DropShips. Such a vehicle would obviously be less combat capable than the Mamono, but you already need to think seriously about providing the Mamono with long-ranged fire support, and that same support could provide the firepower the lighter vehicle would be missing.
I know others may have different opinions and that the Mamono is just the vehicle they're looking for, but even though it's my own creation, it's not the IFV for me, and I'd much rather be using something from across the Davion border.