Rock, I don't have an Atmos set-up so I can't be of much help. You need to decide if you're going 5.1.2 or 5.1.4. I've read .2 is pretty much pointless and .4 is awesome. I've also read you don't need to worry about sound quality up top.

All you're really looking for is some punch up top from lows and dispersion from the highs. You'll get that from the M3IC.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated