Remote.
I've only used the MTH app that one time they had it as a demo for a train at the TCA museum during York week a few years back. (since I don't use a smartphone brought my little iPod Touch with me to try it out when I heard they were doing so)
I've used the Lionchief app a few times at home (basically just to see if it worked - same device, using the iPod Touch).
Wasn't a huge fan of either.
Hoarding remotes. Uh... I mean, the app is awesome, no one buy any remotes, leave them all for me....
-Dave