Specialize in either 6 max, full limit or S&G's???

Playing HE for 18 months...I want to make a decision to specialize in either 6 max, full limit or S&G's. I like to play each of them equally well. I'm an average winning player at $1-2.00 and under. Still have alot to learn. Started with $300 now at $3000..

My goal is to eventually move up to $5.00-$10.00 or higher. I need to focus on one game. Any advice which one is best to play at higher levels?

Most pro's play Full Limit...I suspect that is the answer to my question?

john