A low wing with dihedral becomes a high wing with anhedral when flown inverted.

As you lower the dihedral, you can expect less yaw roll coupling and at some anhedral angle, there will be zero yaw to roll coupling...meaning that the rudder will only yaw the plane without causing any roll. This is desirable in a pattern plane, it lets you use top rudder in a knife edge without haveing to kill the roll with opposite aileron.

I removed the dihedral on one high wing trainer and loved the results, much better aileron response and much easier to fly inverted.