I have always heard of BB/hour in terms of limit play. Grinding it out over a long period of time at the limit tables 10K+ hands would give a pretty good idea of your results.
The swings in NL seem like it would make this number irrelevent. Being a consistant winner over time is really the only thing that matters in NL, no? (and not going broke
) You could calculate it, but I don't see where it would tell you all that much for NL, IMO.
I would be interested to hear why others might think it is useful, though.