Nope. Don't know anything about emotiva.
I have listened to both of them. My impression is you really can't go wrong with either one. Arcam is a bit laid back. So the sound is warmer, or in a negative sense, a tiny bit slower. If you have speakers that have quick response(I am not familiar with the speakers you are using), there should be no problem. Someone said that Arcam doens't offer enough dynamics for movies. I totally disagree. It's great for movies. Dialogue is clean, bass is deep, surround sounds fill the room nicely. I really liked my experience with Arcam. Plus, 2-channel music is very very good also.
B&K is a little bit hard to find in where I live(southern China). I can only listen to a 307 in one of my friend's house. Nevertheless, I liked its sound also. Since you are a B&K user, I am sure you are well familiar with it already.
Now, only if I can find a good deal online and they will ship the unit to me. I will be all set.