My two cents.
It's entirely dependent on the hybrid and on the situation. At the moment I'm running a Nissan March 12R with stock GT-R engine and drivetrain (I borrow-glitched it, I didn't make it and can't figure out how to

). See, it tops out at around 160mph, and people online magically couldn't give two hoots about me in my positively
slow hybrid.
I only enter hybrids into cop, drift and (if I know I'll get beaten) drag lobbies. I wouldn't dream of entering a 'proper' race room and pissing off someone.
EDIT:
And to everyone saying "Ban ALL teh people who use hybrids!!"
Really? Why would Sony ban a (pretty big portion) of the market, potential future customers of their products?