Quickstart reproducing the problem
@devs, I think AbstractSingleSelectChoice needs to tweak the input to be understood by convertes ( my last patch ). I'm just not sure if this is a good idea, because we can't know for sure who will parse the input since one can override the FormComponent#convertInput method.
hrm. what is the usecase for setting a type on a choice component? like you have mentioned - there is no type converstion that is happening here, instead it uses a simple lookup from choice renderer. if anything, we should make calling settype() on it throw an exception.
thought about it some more. the only clear way i see to make this better is to make settype() throw an exception when called on a component that uses an ichoicerenderer.