BB/100 -- What's the upper limit?

[Poker Cat]

Many on these pages claim rates of 1-2.
A few, 3.
I know one ring gamer who was north of 4 after a sample in the 100K's.

It's reasonable to assume that the more tables at a time you play, the lower your win rate. And the more selective you are, the higher. So the real question is what's the highest win rate achievable for a reasonable number of tables (4), with at least 5 players/table. With reasonable selection.
At, let's say, $5 limit to the sky.

Note that I deliberately picked BB/100. BB/hr is a whole different animal, largely because hands/hr varies so much between short/ring and # of players.