All my unifi stuff runs hot. The ERLite 3 and switches, etc. I think they count on using the cases as heatsinks.
Same here. Those things get toasty. I accidentally placed a RPi3 (passively cooled but with a metal case) on top of my USG once and it got hot enough not just to throttle it, but also to cause HDMI artifacting.
Not really. I have a NanoHD and my father in law has one too. His runs really hot and mine is cool to the touch. Mine has more traffic and was made before his NanoHD.
I also have a NanoHD and its acceptable but USG (non-pro) runs so hot that I fear leaving it in a non airconditoned cupboard that my internet exit resides
Yup. My USG and US-8-60W both run hot enough to not want my hand on for very long (the power supplies are pretty warm too).