I can’t directly speak to the Tablo Quad heat issues, but I can speak about my own experiences…
I’ve had a Tablo 4-Tuner unit running flawlessly since Feb 2016.
Shortly after I got my Tablo running, I noticed that it, in my opinion, ran hot. After reading many entries in these forums, this seemed to be the norm.
Like other Tablo devices, this unit is passively convection cooled & has case vents on its sides. I’ve since stood my Tablo on its side to provide a better convection heat flow (now from bottom to top). Since the Tablo 4-Tuner uses an external hard drive, my drive has not been subjected to any excessive heat.
For what it’s worth, here’s a link to a blob article from 2014 where Tablo acknowledges that their devices do run hot… Tablo Quad runs HOT!
Edit: That is the wrong link. Here’s the correct link that I referred to:
How Warm Should My Tablo Be?