Hi PAW; You are correct about rudder-only requiring more dihedral. It's the dihedral that makes the plane bank with rudder only. The original Astro-hog had lots of dihedral, for roll stability, since it was the first (successful) low-wing R/C aircraft. With modern radios and servos, less dihedral is required (in the hands of an experienced pilot).

This is not unusual, though. If you look at most low-wing personal aircraft, Piper Archer, for example, you will see that they have quite a bit of dihedral. The wing tips are up about cabin level.

Happy flying!