Yes, I am looking at the new Yamaha stuff now.
One problem I am running into is trying to find a amp or receiver that will allow me to Biwire my 6 ohm Mirage OM 10's. Every amp or receiver I've looked at can't handle the lower impedance except when the OM 10's are not Biwired. My Castle's are 8 ohm and don't present that problem
The Yamaha can handle it. I've used both sets of terminals to bi-wire 4 ohm speakers and it didn't break a sweat. In fact, you want to leave the impedance switch in the 8 ohm position when running such a configuration.
Check out this video:
http://www.audioholics.com/audio-amplifier/impedance-selector-switch-1
And this one:
http://www.audioholics.com/amplifier-reviews/yamaha-a-s801-amplifier-review
BTW, the amp section is essentially the same between the 501 and 801.