Divernet.com does conduct periodic 'group tests' (I've included a link to one such 'group test'.) If you read the 'Conclusion' you'll see Split Fins are Great!
KICKIN' Back the Power
Conclusion
The fins on test were all high-end power fins. The final results need to be taken in context, as they were the results of one tester with average leg strength finning at his limit of power and endurance against an unmoveable set of scales.
Looking at the final results and compared side by side, I was surprised to see that the three split-fin models performed so well.
In the past other testers have maligned this design and stated that they are no good in a current, but our findings definitely contradict this theory. After all, pulling against a set of scales doesn’t leave any wiggle-room in the outcome.
Split-fins feel as if they’re not pulling their weight, because they’re very easy on the legs, and I think that this may have hoodwinked those who tested them in an open-water environment.
....personally I use (and LOVE) my Apollo Bio fins!
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28 FINS ON TEST
Here Divernet tests the "XT" version which is a somewhat stiffer durometer of rubber compound, versus the regular Bio Fin rubber compound, if someone is looking for that as a feature.
I've got several pairs of 'regular' Bio Fins and one pair of the 'XT's just in case I'm in the mood to have that feature, but so far the 'regular' versions have been just fine.
APOLLO BIOFIN PRO XT (A) £115
width=100% COLOURS 1
SIZES S, M, L, XL
DRY WEIGHT 3.0kg
OVERALL LENGTH 57cm
FOOT POCKET 24cm long
SPEED 4.4kmph
The Japanese Apollo company was the first to run with the Natures Wing split-fin idea, and this XT version of the heavy-weight all-rubber Biofin is more resilient to deformation during finning, and therefore that much more effective. The footpocket of each fin is a bit short for those with long feet, but the results against the speedometer are undeniable. We suggest that you get them with the more expensive stainless-steel fin-strap option.