I have been in numerous similar situations - torn between two. The solution usually is number three or, sometimes, both 1&2.
I will try to simplify a complicated issue. Hope it helps.
1) If you are a drysuit diver with buoyant feet, or if you want to reverse in water, or if you want precision control of your position, then you will want the JetFin or any of its copies: Heavy rubber (buoyancy) and stiff (power, precision control). These are powerfull and good for reversing and good for helicopter turns.
2) If you are a freediver then you will want freediving fins.
3) In other cases, generic plastic fins are usable (split or non-split). I have used both rubber straps (like the ones in Atomic) and spring straps (like in DiveRite). A spring strap is just wonderfull. It is easy to use in the water. You just grab it, put it out and around your leg, and let go. You can do this while standing on one foot in shallow water, or while floating inverted at two metres. No eyes needed
I am sure that there are people who are proficient with plastic clips too, but I find it difficult to hit the slot with the clip. The rubber band also breaks more easily than a spring. The spring strap on those fins seems not to be replaceable. In my JetFins it is replaceable (with some effort) and I can choose from at least three different (almost identical) spring straps.
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I have asked the moderators to move this thread to a suitable forum (e.g. equipment).
---------- Post added June 19th, 2014 at 09:34 AM ----------
One short(?) comment on efficiency. A theoretical discussion will follow. This is NOT based on experience.
No piece of plastic will magically turn you into an athlete. You either do few powerfull kicks (stiff fins) or a million weak ones (floppy fins), and the power (force times time; amount of propulsion) is the same.
If you want good propulsion, I suggest you start surface swimming to improve technique, and that you stand and walk and bicycle more to get strong legs. After that, a stiff fin will server you well. Unless, of course, you are a freediver.
Stiff fins are easier to control while reversing or turning.
I believe that the relevant difference between the fins you are looking at, is the heel strap. The plastic fin folks may correct me.