I hadn't noticed that about the dihedral...and I think you're absolutely right. Setting it up as a standard 3-channel model is the way to go. He should be able to do this without making any major changes to the model.

As far as why it's climbing so severely I assume that's either because the incidence on the main wing 2.5 degrees) is too much for that airfoil or that he needs some (more?) downthrust on the engine.