i found this is in a google search. is it correct?
http://www.pokertips.org/forums/showthread.php?t=43881

this is the important part of the post:
NL25: 5PTBB/100 or less 6-9PTBB/100; 10PTBB/100 or more (max at around 20)
NL50: 4PTBB/100 or less 5-8PTBB/100; 9PTBB/100 or more (max at around 16)
NL100: 3PTBB/100 or less 4-7PTBB/100; 8PTBB/100 or more (max at around 14)
NL200: 2PTBB/100 or less 3-5PTBB/100; 5PTBB/100 or more (max at around 10)
NL400: 1PTBB/100 or less 1-2PTBB/100; 3PTBB/100 or more (max at around 6)
NL1000: A rate of 1PTBB/100 is very very good. 2 is about the max possible. Some people claim more but thats usually unheard of.
if so, what is the point of moving from $400NL to $600NL to $1kNL?

2ptbb/100 hands at $1kNL is $40/100 hands.
6ptbb/100 hands at $400NL is $48/100 hands.

what's the point of moving up?
to improve your game so that you can win more in future when you play $2kNL and $5kNL?
or is this post inaccurate?

also, i'm running at 11.5ptbb/100 hands at $400NL over 13.5k hands. i probably couldn't keep winning at this rate, but i still feel my true winrate is over 6ptbb/100 hands at $400NL and i'm not even the best $400NL player at party.