I currently have the onk 807 and don't have heat issues so to speak.
Is it warm to the touch?Yes,but not egg fry temperatures

I really like the unit but like any other unit it has its little quirks.
Every 3 or 4 days it loses internet connection which an unplug and replug fixes.
Annoying but do-able.
Denon has issues with with its network cards.
Point being,ALL mass produced units will have bad batches here and there.
Hopefully,just a small percentage.Add UPS into the equation and you have raised your odds of getting a lemon.Quality training for UPS delivery men is learning the Olympic hammer throw.

Forums like these where people come for help are probably a very small cross section compared to units sold.
Folks with sweet running units don't need help and don't need to complain and therefore don't post.
Enjoy your unit,once you get it fired up let us know how you like it.
Enjoy your digital nirvana.