I have been through the FF web site and called there to get a better understanding of which model is right for me. The bigger your profile in the water, the stiffer and/or bigger fin they recommend. So for a dry suit diver who is a big guy, they recommend the Extra FF. The Pro model is adaptable to more scuba divers in general. What gets me is according to the Navy test info on the FF site, the regular FF is more productive, with efficiency declining as you go up in fin size and stiffness. I understand that with a larger profile underwater, you need more to push against to overcome the drag, but it seems the more you get away from the original FF design and flexibility, the more FF looses its advantage when compared to other brands and types of fins....and as you move away from the original FF, the prices start going up quite a bit. So, let's say I go for the Pro model....will I be able to get enough umph out of them to push myself against a current while in a dry suit? The Extra FF (even in the standard material...not the even more expensive tan delta material) is out of my price range.