I've only attended a psychology lecture for the mid year exams hosted by TSFX, and I didn't like it one bit. People were eating, drinking and making weird noises up the back and I got the feeling that people were there only for the sake of it (due to parents, can't be stuffed revising by one self etc.).
However, I'm talking about a lecture here - we can't really generalize tutoring to that, can we?
Logically, if you attended a group tuition, it's a bit like attending classes at school, right ~ so what's the point then? At most, they teach you stuff at the tutoring place ahead of time, but it's still up to you to study it, so they're not really helping you any more than your teacher at school. Therefore, whether you go to TSSM or TSFX, the difference would be marginal anyway.
So, I think private tutoring is the better option, because the tutor gets to really know who you are - your weaknesses and things. The downside is that private tutors, from what I hear, cost a bomb!