I have the 4" and it's great. I think the 4.5" would be good too. So far I don't worry about making them float, I bring them in just fast enough to stay on the surface and a pause to let them sink will often trigger a strike if a fish is following but not hitting (which is rare). There are situations that a floating frog could be useful, but those instances are rare enough that I haven't made the foam a priority.
