No major problems,in the 3 years, 1 glass broke (early on), and one ended up getting a bad screen cable connection (and we just opened it and fixed it). The good thing in her type of environment (i.e. all the Prontos are in one place instead of spread out around the world) is that she can have a couple of extra on hand and if one breaks you just download the config and you are up and running in a few minutes.
As for walking away, there are a few things to take into consideration.
1) if it is a total custom job (i.e. buttons used are designed for the room setup) then the setup might be totally useless at someone's home.
2) to do any serious programming you need a specialized cable (might deter some people), on the other hand, the cable is easy to find
here are some ideas off the top of my head if theft is a real concern
1) if all the rooms are the same from the remotes point of view, then it could be on a loaner system from AV dep or securty desk
2) you might be able to make it "built in", something like
[Link: remotecentral.com]