Jeff: If you go with the Onkyo and use your external amps heat should not be a problem.Up to 2012 that has been an issue, they have a recall for those models affected with HDMI board failures, they will repair all models that have this issue until the year 2018. One good thing about Onkyo. The newer model years don't seem to suffer from those problems but they still put out some heat and I would reco a couple of 200mm fans to keep them cool.
I may just wait on the receiver as DTX was just announced with receivers coming out the latter part of this year. I've also been looking at some plug and play RC software (outboard) from DSPeaker anti-mode. This seems like a very viable option for dummies like me. Tells you what's going on and how to fix it with it's own software, no computer needed.