I think most people play a lot of one format and then dabble in other formats when they get bored. I play mainly 6max NL, but play a couple SNGs a week. Stars will be a bit tighter compared to party, but certainly not much better. More often Stars plays are way less aggro than Party players.

Hard to say if it's variance or what. Post hands, ask questions, participate in the forums and you'll quickly find out how to play the games and make lots of money.