I have a pair of M2i's with a PSB 6i sub (12" driver, 225 watts continuous, 600 watts peak). I don't think a big sub is overkill for these speakers; you just have to turn the level control down a bit on the sub

Seriously, the M2i's are REALLY flat down to 80-odd Hz and then roll off fast so they match up nicely with a big sub.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8