I've played from $25NL to $200NL, what i play depends on how well I feel I am playing at the time, and other things such as boredom and impatience come into it, I was thinking about it today and I think thats it boils down to how disciplined you can be and how you handle the emotional swings. Many times i will call down with TPTK just because I am curious to see whether my read was right, a huge leak in my game, I know but I only do this at $25NL, sometimes i'll play 4 tables of $25 for 2 hours not pick up a single hand, get frustrated about how little money I am making think to myself "in two hours ive made what i could make in one blind steal at a $200NL game, and so just cruise up to there and play with scared money." I get impatient at the 25NL as i have discovered bluffing isnt profitable and you NEED cards at that level, and I can go card dead for ages and you get bored/frustrated. I then head up to 200NL and i won't be playing my A game as i just dont want to risk pushing over somebody for 1/4 of my bankroll on what i "think" is a bluff, im playing with scared money there. Although i have broken even at 200NL, I can't play my best there until I have the right mental state and bankroll to try it.