Definitely possible to be more profitable live than online. I have a friend who plays $1/$2 NL at the local casino, and for the most part comes home way ahead. He tried to branch into playing online, and couldn't manage to win at all. It wasn't a matter of not having the proper bankroll / having a bad run, the losing happened pretty consistently over the course of several months. His take is that online players are simply much better at their game than even the regulars at the casino.
I think, though, even though I live in a fairly large city, the pool of NL players that we have is fairly small. We have a couple of casinos, but only one has NL. I don't really have much of a basis to compare limit play live to limit play online -- all of my limit experience has been online, but in my experience, online low-limit play is fairly soft. Though in my NL experience, I like online play better than live play. I have issues when it comes to giving off tells
, so being able to obscure those works nicely for me.
So, I think the answer is really it depends on your personal style and skill set. I could probably play the exact same hands against the same opponents online and live and win more money online than live. For my friend, it would probably be the opposite.
I also wonder if it's easier for online players to transition to live play than it is for live players to transition to online play...any thoughts?