I know my br is good enough for 25 or 50NL, but whenever I take a shot at playing 25NL I always seem to be losing and not playing as comfortable as I am on 10NL (I'm guessing the comfort will come when I play some more on this level). So that's why I aksed for some guidelines about winrate and amount of hands before moving up.
My interpretation is that bankroll "rules" are primarily to account for variance, so you've got that covered.
However, along with that is the element of not playing with scared money. In other words you've got to not be afraid of getting your entire stack in because your stack only represents a small portion of your bankroll. If I recall, FP made some useful comments to joose a long time back when joose was in the opposite situation; he felt confident at higher levels but didn't have the bankroll because he had withdrawn some.
In other words, guidelines are guidelines. If you're rolled, have a decent winrate, even have 10,000+ hands,
but, you still don't feel confident + you're not winning when you take stabs, then unless you feel a need to move up + you're willing to keep absorbing losses, don't do it.
And, moving up or down does not have to be a line you cross never to return. Like others have suggested, find a ratio or pattern for trying the higher level once in a while.