i have heard that they are not that fun behind a boat because popping is weird, and there just isnt very much support in the boots, however sliders are really fun, but they will destroy your skis soooo fast, and there is absolutely no warranty for rail damage, in fact the warranty states as soon as they are used on a non water surface the warranty becomes completely void, and you can definitely notice once they have touched sliders/taps/kickers/etc.
sliders are very different from rails though, having a handle completely changes the way you rotate your spins and the way you pop. i am sure its fun, although only if you have a cable park or a bunch of sliders on a lake that you can ride