I'd highly recommend a Richard Turner video named (along the lines of) Shifts, Hops, and Magical Passes. He discusses a nice variety of each technique.
Personally, I don't actually use either. I don't do a lot of gambling demos, but Dive or Drop Shifts seem to be more useful, because the action happens in a much more confined space and the move is covered by the movement itself, whereas a Hop is more finger movement happening in a larger move. I've seen people that could do each type flawlessly and invisibly, but the Drop Shift seems easier.
Thanks for your thoughts on the matter. I was actually watching that video so sooner or later I'll figure it all out. Trouble is he makes both look so easy and so good! I'm in need of one or the other for a gambling routine right now so I thought I'd get some advice on which might pay off sooner. I'd like to be performing within a month....we'll see how it goes...Thanks again.