Try them. If you like them, buy em and use em. If not, buy blades. Or join the ranks of us who have both. They work and feel differently for everyone that uses them, and all the debate is just personal opinion. The only one that counts is yours.
I forgot option 2- read and argue about them ad naseum here on Scubaboard, then go to the above.
Good points.
I'd like to add the following:
Not all split fins are created equal. Just as not all blade fins are created equal.
Which is better? Split or blade? Well, you might as well ask which paddle/blade fin is better than all the rest, etc.
Check out a couple different blade fins, a couple different split fins, etc.
I've used many different split-fins and there are huge differences. Some split-fins have really strong rails that will provide some serious thrust in the water. Others have
very flexible rails.
With very flexible rails, a split-fin might feel like you are kicking and moving nowhere. I didn't like that feeling at all. If I had only tried the set with ultra-flexible rails, I would probably never have tried another set of split-fins. I'd probably be telling everyone how horrible split-fins are. BTW, that manufacturer recently changed the design of that fin. Haven't tried the new design, so I won't mention which model it is.
Similarly, some blade fins are quite rigid. Others are super flexible. Some have flexible panels in the middle of the fin.
If you are diving with a set of doubles, stage bottles, etc. you'd opt for a different fin than someone who only does boat dives in warm, tropical water with a single tank.
Personally, I generally use a set of full-foot split fins made by Atomic that cost about $80. I use them in current, doing frog-kicks, around Wrecks, etc.
Just my opinion.
Cheers.