I did a fin test once at the Sonoma State U pool with several types and styles of fins. My least favorite were Nova’s. I used black Apollo Bio Fins and liked them better than the Nova’s. I used Scubapro twin jets against the Apollo’s and had mixed results which means they were pretty close to equal. Regular SP Jets provided more power but wore me out faster. Mares Quattro’s had a “dead” spot at the directional switch that I didn’t like, and freediving fins blew them all away.
Made the same comparison several times, also with my wife and my two sons, and the result was always the same: nothing beats free diving fins. They are manufactured of different length and different stiffness, and the best ones have interchangeable blades, so you can set them properly for the real usage, the amount of drag you have to win, etc.
Also consider that jetfins or split fins are the same since decades, no evolution, freediving fins are instead being strongly improved year after year, in the last 20 years both materials and shapes changed incredibly, boosting the performances even further. This resulted in a huge variety of fins and blades, and you need time and tests for selecting the proper high-end freediving fins for your usages. You probably need to own at least two or three sets. And they are very expensive!
But there is no contest: when you need to swim against current, or to carry an heavy load up to surface without the help of your BCD, nothing surpasses their thrust. On the other side, they are soft and elastic, impossible to get cramps if they are of the proper length and stiffness for your legs.
Someone is against long, flat freediving fins as they make it difficult to perform frog kick, which is true. But I and my wife did use them for cave diving (at Capo Caccia, Sardinia) for more than 10 years, and we developed alternative kicking styles, which are more efficient and with less water perturbation.
The most interesting one is the horizontal scissor kick. The legs are kept perfectly straight and perfectly horizontal (not raised up, with flexed knees, with the risk to touch the ceiling of cave destroying the red coral living there).
You slowly open your legs, up to an angle of +/- 45° (that is 90° in total) keeping the fins flat (horizontal blade), so they will not create a significant reverse drag. When the legs are open wide, you close them quickly, angling the fins so that their blades are almost vertical, and they squeeze the water one against the other (the lower face of the blades will be face to face at the end of the squeeze). This pushes you forward, with the water being pushed backward (not down, not up). At this point you are launched fast, in a very hydrodynamic position with minimal drag, and you stay still taking profit of inertia.
A good horizontal scissor kick with long freediving fins can make you advance up to 5-6 meters, against the 1.5-2 meters you get with traditional frog kick and jetfins. And keeping a much more streamlined profile, as the legs are always perfectly straight, no risk to touch the bottom with your knees or the ceiling with your heels.
Of course there is also a reverse horizontal scissor kick (much less efficient, indeed) for going backwards inside a tunnel: keep the blades vertical while enlarging quickly your legs, and then close them more slowly keeping the blades horizontal.
No training agency actually suggests to use long freediving fins for cave diving, nor teaches these special kicking styles. I and my wife are a bit heretic here...
) All I want to say is this : one must not think he could use model A like model B. You have to adapt your technique to your fins and besides we're not the same (height, weight, experience, stamina, goals in a dive, diving site...).
