Will the M2i tolerate an 80Hz crossover to a sub? Or does that leave a depressed bass region around 60-80Hz. (I understand that the M2i does extend below 80Hz, but since the crossover is going roll off the sub somewhat below 80Hz, I think there might still be a problem.)

Greg, the 80hz crossover on the 6070 will work perfectly with the M22s. The whole idea is to relieve the mains and the receiver amps from part of the bass load. The sub completely fills in for the decreased mains output below 80hz and does a better job than the M22s could do in that area(assuming that it's a decent sub).

That's good (that 80Hz crossover is ok for M22). But I was asking about M2i.

At +/- 3 dB to 70Hz, an 80Hz crossover should still be fine.

Greg, as semi indicated, there should be little difference between the M22 and M2 in that respect. If you examine the response curves in the NRC measurements which are part of the SoundStage reviews which you can find at ecoustics.com, you'll see that the M2 can handle the area down to 80hz.