I totally agree that GPS flying with TLAR is a good thing, but you need to remember that GPS can fail and you need a backup of some sort. If you only have other GPS as backup then those would be useless if the satellites themselves stop working.
Anyway, if you always know where you are with the TLAR picture, then creating a new flight plan on the spot when GPS fails is as simple as a diversion practise during flight training. We're here, let's go there.
The chance of all GPS to fail is very low, and multiple redundant GPS devices backed up with a good old paper map is very sufficient in my opinion.