I moved from 10NL with $100 to 50NL with $1,000 in about 3 months playing 6max the whole way.

Those levels (10NL and 25NL is you're playing a site like PokerStars) are very very +EV and you can make a lot more than you think in a very short period of time.

I can't say much about .25/.50 LHE because I started at .50/1 in LHE.