A quick update for those who still care :P
I returned the Onkyo 876 today and instead picked up a Denon 3808 (albeit a demo model) for the same price. Price/Value the Onkyo was probably better but it just didn't sit right with me. The heat issue seemed to be pretty well documented and even though it only rarely resulted in shutdown problems or artifacts I still can't imagine that heat is good for any kind of electronics. Regardless of what kind of heat a component was designed to take it's not going to last as long as if it ran cooler, and I want my receiver to last a long time. I also don't want to pay 1200 for a component and then have to worry about aftermarket cooling for it :| It also seemed like Onkyo had really poor customer service and many people dropped their products after their experiences. I've read nothing but great things about Denons and their reliability and seen many Axiomites using older models with absolutely no problems. Plus, it seems like the 3808 is the poster boy receiver for Axiom speakers.
Now I just have to wait for the speakers to actually arrive so I can set it up and see how it runs
