The pool pilot digital looks like the way to go. The Goldline product seems to fall a little short, but that is also reflected in the cost.
Temp compensation, if it works, I think is a very important feature. What's your biased opinon? I am already leaning your way.
***Temp compensation is designed to aleviate you from having to adjust the output of the system, based upon water temperature changes. It also allows us to operate under cold water conditions and prevent premature cell wear from operating when the water temperatures drop.

Space: I have a ~36" section of output pipe that spans a space to add a heater. Currently an inline hayward chlorinator is installed in this run. The plumbing is all 1 1/2" PVC. Can't change that; any issues?
***That should be enough space to plumb both the heater and salt system. The fact that you've got 1.5" plumbing will not be a problem either.