2-3 handed Winrates

[FrankTheTank]

This is something I haven't seen discussed much. For 6max and full ring games, around 3bb/100 seems to be the ceiling on what a good player could realistically earn over the long run past a certain level, but what winrates are possible for 2 and 3 handed? I'm sure it's higher than 3bb/100, but there doesn't seem to be any consensus. For that matter, is the 3bb number based on any math, or just experience? Thoughts?