I just moved to the 3/6 in the past few days. I've been playing at the PokerRoom 2/4 for a while and finally cleared all my bonuses on that network and I hate the rake and for some reason I spew at 5max tables.
I've noticed a lot of aggression at the 3/6. Guys won't hesitate to 3 bet you preflop with a mid pocket pair and continue betting when there's overcards on the flop. Try not to get too caught up in the aggression, it's easy to start going crazy against some maniac with something like middle pair to find out he actually did have something this time.
I usually pay a lot of attention to PAHud and see what these guys are showing down, try to take lots of notes for the first few orbits, it helps with your overall read i've found.
I'm sure you'll get lots of better info, and I look forward to it as well.
Good luck at the tables, hopefully you'll find guys like
this
-B