1. There should be no alt limit in the RC as long it cannot calculate real alt over ground
2. Flying behind a hill and using rth after it or losing signal while having set 60 rth altitude will crash it into the trees.
3. Flying up a mountain will likely crash it when it stops ascending just over ground because of fictious alt limit
Actually if you take off from the top of a hill/mountain and you traverse down the mountain/hill and loose signal the quad would ascend to its RTH first, which if you took off from the top of a hill/mountain that is your 0 foot starting point. It would end up say 60 feet above your takeoff point. So it should be ok as long as the other hills are lower than where you started.
The reason is that if you take off from a higher advantage point as you descend you will see a negative height on your display. Very strange I know. But they don't take the actual height as seen by GPS and display it. It only knows that if you take off on a hill that's 0 starting height and if you fly down the hill you will see a negative value for your height. If the quad looses connection or you press RTH it will ascend to its height you programmed and RTH which means it will go above your starting point. Not just up say 60 feet from where it's at.
With that said you should always be in sight of course but there are times where I've been a couple hundred yards away from the quad and I've lost connection with it when flying in high density RF interference.