[kjflyfish]

I'll give you my perspective on Gary Fisher Powerfins. They rock. The kick stroke is longer and easier and I found myself kicking slower to get the same propulsion, which is great for conserving energy. Unfortunately, I cracked my barely used Fishers at the screw holes. I have heard of very few incidences like mine, so I don't think it's prevalent. Just be careful to make sure the screw holes are drilled ever so slightly oversized. I would also check out Sask's fin review on Spearboard, where he talks about the DiveR fins. These are the same concept as the Fisher fins and apparently, they have never recieved a complaint about breakage and come with a lifetime warranty.

All that said, if your carbons are still going strong, it seems like new carbons would be a good idea.