Well in the bipes I've built I have put the top wing at 0-0, and the bottom slightly positive, which I think gives an over all negative incidence. Bipes have a lot of lift, it seems to me that + incidence in the top is going to give even more lift, hence the down thrust on FF models. Without the down thrust they would want to loop.
It will be interesting to see what happens when you fly. I have a F6C that has throttle (.40) power, it wants to loop at high speed, and the wings are 0-0. But it does have a Clark Y airfoil.
John