I have instructed RC since the 1970's and I'd say it depends on your wife. If she has good hand-eye coordination, then skip the dihedral. Is she good at video games, does she play tennis well? Or is she an athletic klutz. You have to make this call.

As for a flat wing trainer, I'd go for the Avistar, which has a semi-symmetrical airfoil or a Stick. My buddy Ugo Ferrari has an Avistar with a flat wing and an OS .46FX. It sings and does everything except 3D. It still looks pretty nice, where as a Stick is, well, a Stick. As I recall, women tend to be bigger in the esthetics department than men.