Here's my deal on 3D'in with 4 channels.

I only use 4 on my foamys. The ail's are Y'd and everything else is standard... however while I do not use all the channels offered by my 8103, I do use exop. Without expo my latest plane would be a bear to fly, as it is I've dorked it a couple of times while torquing when it responded a lot faster than my last foamy.