the main benefits of race fuel ive noticed are:
1. consistent product - theres no risk of water or other contaminants in a fresh pail of race gas. whats on the label is what you get.
2. better throttle response - diff fuel formulas, esp those with extra oxygen, can make the throttle feel crisper.
3. more hp - consistency allows for a better tune, which can increase HP. more oxygen is more HP when tuned properly.
my engine builder said to use race gas, so I use race gas. F&L Xtreme100 is what I use at amateur events. VP MGP is required for MotoAmerica events. both fuels are very close in specific gravity, O2 content, etc. so I dont even bother switching maps. VP MGP is 94 octane, so its not like I need the extra octane in Xtreme100. both are ~$12/gal.
modern motorcycle engines arent like classic big block V8s. you dont need a ton of octane to prevent detonation in huge cylinders with poorly designed heads. VP MR12 is the go-to fuel for making great HP in sportbikes, as it has a ton of oxygen. its only 94 octane. however, it leaves a residue on the head, should not be left in the motorcycle, and will make any trailer or garage smell like death. so there are definite drawbacks.
if someone is serious about racing, they'll build their engine. cut the valve seats, time the cams, get the head gasket thickness perfect, etc. then itll go on the dyno. if they spend all that $$, they should use race gas to protect that investment and for better performance.
would I ever use race gas in a stock engine? nope.