I seriously don't think your bankroll can be "too big" for a limit. Unless your playing at the micros, there really isn't a rush to move up. Make sure you can beat the game and build a big enough BR for the next level. Also sometimes it may be more profitable to play at the smaller limit if the games are definately softer.

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“There's no sense in being precise when you don't even know what you're talking about.” - John von Neumann