My problem is I'm just too damn picky. Forgetting sonic qualities for the moment (I obviously prefer the V3 as I run one), my issues with the MMe:
[1] half-rack dimensions are a bit awkward for portable gear
[2] unprotected knobs/switches
[3] internal high/low gain jumpers instead of external switch
[4] poor level meters
[5] recessed cal pots when running low gain
[6] non-locking XLRs
[7] non-locking power cable
[8] inability to output 16- and 24-bit simultaneously (I vaguely recall that this can be done, actually, via S/PDIF 16-bit and USB 24-bit)
My issues with the V3:
[1] no soft-limit
[2] locking power connector longer than right-angle XLRs
[3] inability to output 16- and 24-bit simultaneously
[3] internal high/low gain jumpers instead of external switch
[4] internal M-S/stereo jumpers instead of external switch
That said, there's plenty to love about each unit - but it's always easier to moan about real or perceived shortcomings than to sing praises.