chillyinC, Your point is well taken, also those who, like me--just happened to run into something that works. Not that I disagree really (because I really don't know for sure), but are you speaking from a lot of experience observing divers with splits that they do in fact kick up more silt/sand, etc.? To be honest, this is the first I've heard of it (though I obviously have heard of all the other negatives). In my observations on those dives where I was with other divers (charters, etc.), I rarely have seen split fins being used. I suppose I have, but it's certainly far from common. Is it possible that the divers you saw creating a mess with splits were just poor divers? I also recall on my solo diving before winning the splits, I would disturb the silt if too close to the bottom with the non-splits I used. Of course, either way, when with others I am careful not to stir things up.
If there are other fins that work just as well for cramp prevention (and this is what the OP is concerned with) and have other benefits (like more power), great--go for it. I didn't even know that splits were good for cramps when I got them. Someone mentioned it to me YEARS later. In fact, in my 4 years of DMing I can't recall anyone in the shop (Instructors, DMs, etc.) discussing fins with regard to cramping. Thus I have no idea what other style/brand of fin would also be good in that regard.
Going back to my first post, I honestly don't even know if the splits eliminated my cramping because as I mentioned, I believe I started the potassium pills about the same time (maybe 6-7 years ago). So one of the two things or both together worked in my case.
Perhaps part of this equation is that I don't think it is very common for people to have such severe cramping as the OP and myself (used to). I've seen the odd student diver (and others) cramping up a bit, but that's usually chalked up to muscles that haven't been used as much before. So the usual remedies discussed here probably work fine for most (better diet, more hydration, regular diving, etc.).
Not relevant, but interesting that I am able to frog kick quite well with the splits but not back kick, though boulderjohn said it is possible.