IS 'mechs do have a cool factor that beats pretty much all clan 'mechs, with the exception of the Timber Wolf because absolutely nothing has ever been as cool imo, maybe even the Nova Cat too, I can admit in an extended slugging match the IS 'mechs can stay in the fight for longer, assuming their pilots are decent.
A BattleTech game on here could be quite fun actually, if you can think of a good way to make it work and maybe find enough players, although that depends on the style you do it in.