it really just depends on your goals. some people get them to have cool looking trick parts on their bike. others, like me, get them for the track to gain more ground clearance for the turns.
in my opinion, they shouldn't be on a street bike. for one, if you're dragging pegs on the street you're asking for trouble. two: if you're dragging pegs and switch to rearsets, your next peice to drag is the kickstand mount, which is very dangerous (we cut them off for track bikes). three: thats a lot of money to spend for looks.
