I've used (and still have) C4 carbons and Matrix fibreglass blades. I now use Cressi 3000LD plastics because I've found I get minimal performance benefit from carbon/glass. They do feel more 'springy' but that doesn't necessarily translate to better performance. After a day of testing a number of fins in relatively controlled conditions (repeat 30m dives on a line) and graphing the dive profiles, I found all fins of the same stiffness produced nearly identical graphs regardless of what material they were made of. My subjective 'tiredness level' at the end of the dive was also the same, as far as that can be measured.
I know there would more statistically sound ways of testing fin efficiency. However this is the best I could realistically do, and it was enough to convince me that there was no need to go past the Cressis.
I seem to be doing this a lot lately, dropping into threads and being all contentious. Oh well...
Note: I tested each fin twice (not back-to-back!) and averaged the results, which were practically identical anyway. In the future I would like to do a more comprehensive, blind test that includes monofins, and maybe even some way of restricting kicking cadence and amplitude to get things consistent.
All the fins were within 1s of each other (1:17 - 1:18) with the exception of the C430s and Mustang 30s which were slower (the colours can be hard to distinguish, sorry). I gave these ones another go just to make sure - same result. Bit stiff for me I think.
