[alexrom1207]

All other things being equal, a softer fin will result in less power, but depending on your swimming style, may provide you better movement on the surface.
If you want to go with the c4 Flap 30 you will get a good surface and depth fin (however you will pay for it $440)
If you want to save the money and you like the cressi footpocket, the Gara3000ld is probably a good fin. Made for surface swimming, good for depths up to 25m. Basically indestructible. And if you're having leg/ankle cramps it's probably a good change from the gara 2000. I've never tried carbon fins but I've heard people who use them love them, so hopefully someone will give you some feedback on them. Happy shopping.