You might as well go down to 40 tons and have a Myrmidon, but if not then Manticore is just fine.
But the increased strategic movement costs are a real turn off, for me at least, I'd rather have it be 10-tons lighter and be able to field 2 of them then just one
The alternate method would be to use 2 MML-5's in place of the normal missile launchers, which is probably the better solution
Which goes back to the question of what you want in a tank, and where it fits your TO&E. I personally LIKE the Myrmidon, it's a good unit, but...it's not hte all-arounder that the Manticore (3025 version) is. The Manticore is a Heavy tank, for the Main Battle. i.e. it covers a wide number of bases adequately with enough armor and speed that it's not going to hinder the ground offensive by having to flank just to keep up.
The Myrm (or lighter tanks in the same general category) is a faster ride, true-but it lacks the flexibility and toughness that you get with a Manticore-as would the design you suggest. An LPL and MML 5's is just another city brawler-in a market choked with them. There really aren't very many
well designed MBT's out there. (the 3058 Manticore is another 'yet another city brawler" mistake-more expensive than a Demolisher, with nothing to show for it but reduced damage and a slight increase in speed that is irrelevant for the static, close-range defenses it's designed for...)
In the Real world, Tanks are designed and rated by three base criteria:
Armor, Speed, firepower.
In BT, tanks have a fourth criteria that goes in...
Cost.
The Manticore sits on that four-legged range about evenly (3025 version, not the "Upgrade").
Good armor
Good firepower
Useful speed
Costs less than a comparable 'mech.
YES there are some defects-the bow-mounted ML, for instance *(FOUR tons, not ten-1 ton for the laser, three for the heat sinks) could be lost and the design wouldn't feel it, or be replaced by an SRM rack, vehicle flamer, or machine-guns, or a boost to the plating there, without batting an eyelash, or if you have money, swap it for C3 and a Beagle or somesuch, or a TC... but the point is, even with that defect, it sits in a rare class in Battletech: it works in ALL eras, from Star League to Republic, and outperforms most of its competitors in the four criteria;
A tank with better plating, guns, and speed is going to cost MORE, usually by LOTS.
A tank with better armor, guns and Cost, is going to be slower
A tank with better Speed and guns and cost will have thinner armor
A Tank with better armor, speed and cost will have less firepower.
This is what makes the Manticore such a good buy for...everyone. at least, the ORIGINAL FIT Manticore (TRO 3026, accept no canon substitutes).
It
sets the standard for an MBT, that is, not a "Massive Battle Tank", but a "Main Battle Tank"-as in one that is useful for all the roles one might logically USE a heavy class tank for, as opposed to most of its' competition, which only work well in one or two NARROW roles, or (as in the case of the Manteuffel) whose cost is so extreem that you can buy a good heavy
battlemech at the same price-one that matches it on armor, speed firepower, AND COST with ease and without the motive crit problem.
There are VERY few tanks in the game that can show up in nearly any terrain that allows a tank to operate, in virtually all eras, and still grant their users a reasonable chance of success, even against "Technologically superior" opponents. The Manticore is one of those rare units. SPECIFICALLY the TRO 3026 Manticore.
This makes it a "Benchmark" unit-one by which subsequent designs can be judged honestly to evaluate their game-performance.