I came to Sonar in the X1 cycle and used the ProChannel exclusively from the off. I've never found a good reason to use the FX Bin, and to be quite frank it seems like a PITA in comparison. There's just not enough space to work with, especially if you're into using long chains. It's too cramped and you can't see the full chain at a glance. Whereas with the ProChannel its very easy to see my full chain and know exactly what's going on.
My only gripe is that the ProChannel FX Chains should be resizable on the vertical axis. They're a waste of vertical space if you only have one effect in there. Sometimes you need to use 2 or 3 FX Chains on a track (say you want to insert single VST's in between your PC modules) and it all adds up. If we could collapse or resize FX chains I'd be very happy.