a few years ago, before LA endorsed the product, i used it for about six to eight months.
if you go to their website, they published a study on elite cyclists before and after using FRS. i am relying on memory here, but I recall they claimed a 2% - 3% improvement in certain cycling metrics (either FTP or VO2 Max, or perceived exertion) among those who used FRS. i think the study was done at the University of Santa Barbara. i think their claim to fame was something called Quercitin (or something similar sounding). i think it was a special anti-oxident that somehow tied to endurance benefits.
Honestly, i do not recall seeing any benefits, except being happy that i was getting my anti-oxidents. I stopped using it because i just didn't see the value of $30 - $50 per month (i was on their "auto ship" program). i decided i would spend money on a better eletrolyte drink & a recovery drink instead (First Endurance EFS and Ultragen).