I jumped from the Peachtree separates to the Nova 500 when they offered an upgrade deal. The separates were powering my Magnepan 1.7s well but I felt they'd be better with the extra power the 500 offered.
Frankly the difference is huge. I've got a noticeable increase in range and separation at high volumes and plenty of nuance and detail when playing at lesser levels.
I'm a very happy camper. That said, how are you doing with your 500?