I've had an MRX720 for about 3/4 years.
Personally I still think it's the cats meow. Does everything I need. There's no Bluetooth is about the only thing lacking from most other AVRs. And DTS Playfi is so so
The ARC has recently been up dated we were getting most speaker set to their maxes from it. Mind you most on HTF I think, didn't have any other issues with it and it still worked great for them and I.