Most of my experience with amplifiers in that price range is for used products, so not much help (Carver, Adcom, McIntosh, etc.)
Some QSC are excellent. I don't really know about the newer import models. I've not tried the Stewart you're looking at, I have owned one of their small ones a long time, I wouldn't buy it again. Hafler is out of business, so if you don't want used....
Adcom are typically good amps, not sure what's in that price range new; the older 535/535-II/535-IIL/545 etc. have good history, but again are discontinued.
I've been curious a while about AudioSource, have heard good things. I can't offer any opinions since I've never owned one. They're in Oregon, owned by PhoenixGold now, who also bought most of Carver several years ago --
http://www.audiosource.net/amplifiers.html Maybe someone else has tried and can comment. I think you can get them at Circuit City now, they'll do a 30-day trial or whatever.
Steve