engine brake while towing?

I use cruise control all the time on the flat and I think there is something to what you say in regard to the truck looking at speed instead of brake application for a reference but I still don't like it descending grades because as I have said before, all it sees is speed and will do anything it has to in order to maintain that speed including shifting when you don't want it to. Often, a little application of the service brakes is all I need to check a small speed increase that certainly doesn't warrant a down shift and then having to add power because I have too much braking from the EB. For the same reason, when going up hills, I turn cruise off when approaching the hill because waiting for the the transmission to shift down automatically is much more abrupt than if I preempt it by shifting down earlier. When towing, my truck will often wait so long to downshift that it goes from sixth directly to fourth, but manually shifting to fifth before that happens is much smoother and often all I need.

No doubt the later trucks are more sophisticated and better in this respect but my EB only has two settings, On and Off.

I often monitor transmission temperature on hills and never have an issue with it getting hot. As long as the torque converter and clutches stay locked, temperatures should never rise very much on hills.