The string that comes with the Sage is pretty bad--way overbuilt dacron. I can't speak for the "generic" FF string that comes from 3 Rivers, but I do know that I toss the "factory" string and make a good one (8125, 8190, or Dynaflight '97) that fits it. Night and day difference.
What kind of difference will I notice?
I am getting pretty good groups out to 20 yards and open up around 30.
Is FF quieter? Noisier?
Will my arrows lose less altitude over a further distance? Would my 2114 arrows fly better out of FF because the spine weight is a bit over what is needed for a 45# draw, or would they fly worse?
I may just buy one to try it, but it would be nice to know what I should expect. Maybe I couldn't even tell a difference because I'm pretty green?