I had a 6700mp. Never had any proglems with it at all. Good little HU. I just upgraded to 8600mp. WoW very impressed. If you can affard to cough up a little extra cash you should get the 8600 or the 960 it makes a world of diffrence.
I own a premier 680. love the thing to death. lil hard to get used to at first, but once you understand it... you will love it. it can control an active setup also..