RE: what is the benefit??
I think the softer cam will be quieter, which is the big advantage in my mind. I don't think I'd call the F cam a soft cam. Just not as aggressive as the I cam. The speed of the F cam is not too shabby, given the draw force curve. I bought a 70# Liberty rather than a 60# Patriot because I think it will be faster when shooting the same arrow (375 gr). The Liberty also has less recoil and vibration, not to mention being quieter, with an added 1/2" of brace height.