The heat issue seems to run from unit to unit. I've read that the Onkyo 805 runs hot for some people, yet mine has never gotten hotter than room temperature. I can't explain this.
My post on this seems to have gone to the bit bucket. Basically my 605 is never warm to the touch either, even after a 6 hour marathon. I wonder if the heat problem is experienced by people who drive inefficient speakers to loud levels while keeping the receiver in an enclosed space. Mine is on an open shelf with good circulation.