Hi
Okay I have two questions then,
Applying the sanity test.
There are several cargo plane (C17, Galaxy and the dirty bog Antanov etc) that I know of plus a passenger aircraft ( BA something or other four engined city hopper) and a trainer(Gnat) all have anhedral that doesnt make sense to me as I wouldlt think they wouldnt intentionally make these aircraft unstable. A fighter yes I can see your arguement these types of plane I would doubt it.

Second if what you say is true and you built a model with an Anhedral wing would fitting a Gyro on the roll axis help to tame it?

Mike