I started a thread on these 3 months ago or so, and there a number of users with them that have been seeing very good results.... ARC is a scaled down version of their preamp variety with a bit less processing power. Regardless, its still proving to be an excellent room correction solution with some very good quality internal amps that reach their rated specs compared to many other brands that can't seem to hit the mark....
http://www.avsforum.com/avs-vb/showthread.php?t=1289533
Anthems ARC - IMO is still better then Audyssey....