I have a remote in for upgrade with 4.2 software, and I've run it with the 6.1 version of software in my TIU on the layout with no issues. It seems that until a significant change in the protocol between the remote and the TIU happened, the RF link would still be fine. I still think there's a place for this product idea.
There is another thread here about issues with the wifi app and the latest Apple iPad OS. The implication is that changes will have to be implemented in the app to keep up with changes in OSes. My experience with Apple OSes is they make many apps obsolete in less than 5 years and if not the App then the hardware it resides on.
Who knows, the remotes may well outlive any software dependent alternative.
John and Pete, having dealt with upgrades in both hardware and software, including the issues of obsolescence (hey I spelled that right first try) in the telecom industry, I think both of you have valid points. If we didn't have to constantly increase the bandwidth and features of the Internet, and deal with security issues, we could run almost any equipment indefinitely. That is what we were doing with the old SONET (Synchronous Optical Network). Usually when something broke, it was when we pushed a new software upgrade and some other feature stopped working. In a closed system, like our layouts, we could run the same system at the same software level for many years. Granted I don't expect the hardware in consumer electronics to be as reliable as on commercial hardware, but what usually breaks? Plastic thumbwheels?