[tongni]

This may be just me, but I play tighter 4 handed in the CO than 10 handed a fair amount of the time, because the opportunities for you to steal are much less in full ring, the button or blinds won't really 3bet you as much because it's not as obvious that you are stealing. However, if you are openraising UTG/CO 4 handed, it will become really clear you are opening light and the button of course won't want to give up his positional advantage and start 3betting you a lot, as well as the blinds.

I think the fast and furious pace of 3-4 handed HE can often lead to breakdowns in preflop stragety though. It's really easy to get pissed and then just start open raising 60%.