I had a T-Mobile S7 Edge that only got hot when it was charging, on Waze, and at least one other active app (eg. I often play YouTube videos in the background while driving).
Otherwise it wasn't too bad. I sold it to get the Note7. After first replacement of the Note7, I got the unlocked Olympic edition S7 Edge from BB. It got crazy hot. I wonder if it's Band 12 LTE was simply not as good as the T-Mobile one because it's signal wasn't as good.
I returned it when I got the 2nd Note7. Now I'm back on a T-Mobile S7 Edge as of Monday. It's somewhere in between the two. Hotter than my original, but no where near as bad as the unlocked Olympic. But I've had two other issues with it, one now fixed. GPS was not accurate on Waze. Uninstalling and reinstalling sorted that, and now two random reboots so far. Starting to wonder if I should give up on Sammy for now and switch to something else but not sure what. Not impressed enough with the Pixel XL for its price. Maybe LG V20, but if Samsung has some stability issues, LG has a lot more historically.