I too suffered the fate of HDMI switching/hardware issues on a mid-level Onkyo two years ago. And like many, I purchased Onkyo because it [seemed] to offer the most band for my dollar. Exactly 30 days after set up, HDMI inputs began to blow. Crutchfield replaced it--I actually chose the same Onkyo again. And 30 days later? Yes, you guessed it. But this time I lost more HDMI inputs than on the original one. Both of mine ran very hot and I had both of them in an open rack where they were ventilated on all sides and with about a foot of space above.
I spoke with Dallas at Crutchfield this past weekend and he looked up the exact model that I purchased and was able to tell me that the problem on my receiver had been traced back to a specific faulty component and that [theoretically at least] Onkyo had fixed the problem by switching suppliers, which I think someone else mentioned. This was not good enough for me. I'll never buy Onkyo again, though ironically, I have a 35+ year old Onkyo stereo receiver that someone gave to me a long time ago and it's a tank. It just won't die.
I have a Yamaha now with no issues and it runs very cool. --It's in the same rack as the Onkyos were.
I think you'll be happy with your Marantz.