I'm running an all maggie surround system as well. 1.6s in the front (phantom center for now), MMG sides and MGMC1 rears. I have a 4 channel Exodus (hypex class D based) amp running the surrounds, but the 1.6s are actively crossed at 100Hz each to its own dipole dual 15" woofer cabinet so the setup is flat down to about 25, wih some more in room response as well. Then I have a sub as well The 1.6s and woofers are all run by two Crown macrotech 2400s (about 8-900 wpc into 4 ohms). My house is a very open floor plan, and I run things at full reference often, with very minimal distortion.

In other words, I think one of the secrets to using maggies for HT is to unload the low end from them and have plenty of power to spare if you are going for full theater like sound levels. As for the effect of the dipole design on surround character, I think the issue there is placement. I have a enthusiastic and supporting wife, so big black cloth covered panels all over the family room is OK. My speakers are all placed right where they should be, but the room itself has uneven architecture. Once I applied my Onkyo 885's room correction, I noticed a pretty definite improvement in the channel steering, so the 997 would be a definite asset in a similar situation.

Additionally, I'd argue that a maggie setup can have just as much punch as box speakers if you augment the low end as I have. IMO magnepan is way too generous with their quoted lowend capability, but then that the practical side of marketing needs I guess. I personally found my 1.6s o be pretty weak from 70-80 Hz on down before I built the woofer cabinets.