Snow Tomb is one of my favorites, but I think the move is too different from Rock Tomb for it to not be confusing.
Icefall feels more solid than snowfall; snowfall gives me the impression of white Christmases and sledding, while icefall seems more glacial.
I wish there was a really awesome-sounding name for those giant chunks of glacier that sometimes fall off, but all I've seen is icefall which seems a bit too on-the-nose and not as much pizzazz as I'd like :P