So you'd call the Nova Prime or Turkina D a critseeker?
Take a look at the Turk
E. The HAG 40 is almost superfluous.
I don't see as there is any reason it shouldn't be a thing in universe either. The explanation that is out there for why normal mechs can't simply be modified the same way has to do with some blanket reasoning about weight distribution and the way omni mechs are constructed and possibly gyros calibrated as compared to a standard battle mech. I could be wrong and someone can feel free to correct me. That is part of the reason we have magnetic clamps rules that we have now. Even if they don't really make sense.
Or swarm a friendly in one turn then and then simply elect not to fire any weapons in the following turn. If you note TW, page 223, "If the swarming infantry unit stays on the ’Mech, it
may make normal arm-mounted weapon attacks."
Based on some simulations I ran a while back, there is an appeal to massed LRM-5 racks over the larger launchers, especially 20's. In both IS and Clan tech, there is always a weight savings in using an equivalent number of LRM-5's over 10's, 15's or 20's, and in the case of the IS LRM-20, you also save a crit. Caveat, the weight/size advantage does not apply to eLRM's or nLRM's.
I ran some monte-carlo simulations that randomly selected a THN, rolled 2D6 for one LRM20. Misses were treated as 0 damage, but hits were checked against the Cluster Hits table. Then it used the same THN number for 4 LRM-5's, and treated the results the same. I don't recall which one came out on top but I do recall that difference after a million or so comparisons was on the order of 0.1 points of damage.
This scheme also has some advantages. Instead of a single 4 crit Clan LRM-20, you now have 4, 1 crit weapons. You can take a critical hit, lose a launcher and keep sending hate and discontent down range, albeit at a lower volume.
The size and weight advantages break down once Artemis comes into play. The weigh/size advantage holds for MRM's and Streak LRM's but there is still some testing to see if the MRM's +1 THN, or the Streak-ness changes the results.
The downside, however is heat. LRM-15 and-20 racks are cooler than equivalent LRM-5's. This becomes a bigger deal if you replace a Salamander's IS 3 LRM-20's at 18 Heat with 15 LRM-5's at 30 heat :o .
Which brings me to something else that I haven't seen mentioned. TSM has it's uses on non-melee 'mechs. Use it on heat hogs, to get out of dodge. Instead of designing so that you can alpha or fire several brackets and stay under +5 Heat, so that you can run away and cool off, aim to be +10-13 Heat after a salvo. Instead of being -2MP, you are now +1. The GTFO maneuver just got a bit easier.