I believe the only difference between the NHT A1's and the M2200's is aesthetic at this point since the M2200 now incorporates the balanced inputs. The A1's do have the front undercarriage lights but those may not be important to you. The M2200's do have (IMO) a nicer setup for the trigger ON/OFF power with the 1/8" plug instead of direct wire.

NHT does play the number game in specing the amp by rating the power at 6 ohm instead of 8 ohm but I don't think it fools anyone.

If it matters I have the NHT A1's but I also use an Outlaw 770.

NHT also announced a while back a new amp based on the A1/M2200 design. It was a stereo 100 watt/channel amp in the same chassis as the A1. I'll bet Outlaw has one out soon.