It is all personal preference really. I bought a new Protec last year and they sent the 75% modules on it . I just didnt like the feel of the higher letoff . When the cam rolled over into the letoff it felt too abrupt whereas the 65% seems to just ease into the letoff and letting down is a whole lot easier with the lower letoff to me. There really wasnt much of a speed difference between the two different letoffs . I think I only gained about 2 FPS going to the 65% but I am just personally more comfortable with the lower letoff.