[Copernicus]

Average stack is just the total starting chips divided by number of players remaining, so the relationship of average stack to blinds is a function of how quickly players are eliminated and how quickly blinds increase. Assuming that blinds follow the same pattern (increase the same amount at the same time or after the same number of hands) then that factor is gone, so how quickly are players eliminated?

Certainly in NL players are eliminated faster earlier in the tournament than they are at Limit, so the average stack will be higher in terms of big blinds. That relationship should continue throughout the tournament, and you would eventually get heads up with a higher average stack relative to the blinds. That, in turn, should result in luck being a little less of a factor in the late stages in NL than L, and that is certainly my experience.

As noted earlier, though, position is usually a more important consideration than size of the stack, and that is better estimated from median stacks than average. Unfortunately sites post average not median, except for Stars, where you always know where you stand, with exact chip counts, another reason I like it best. (Although with my bank recently changing its policy on using credit cards at poker sites, funding/withdrawing at Stars is quite a bit more difficult than some other sites.)