Although I have not personally heard the amps you ask about a friend demoed both and suggested that if one has the funds the new Bryston 7B³ are the way to go. She said (in your words) a better performance.
If you can't demo them for yourself, why don't you call a dealer and ask them to describe the difference in sound?
If you can't demo them for yourself, why don't you call a dealer and ask them to describe the difference in sound?