Ah, yes, I see what you mean now. ^^
As you said, .referential() is just a little helper for the few cases where the reference type is Copy, so I don't think it's worth all this trouble just to keep it. .with_referential(|r| *r) is ugly but it works, if it wasn't obvious enough from the whole RefType thing, my library doesn't quite have clean-looking code as a main concern. 