First, I'd like to say that I am a person who's other hobby is spending a lot of time researching dog's pedigrees and different breed's standards- I have a lot of respect for the individual breeds because of their purposes and diversity, especially the regional differences that occur (like we're talking about here.) I think it's an insult to the breeds to cross them and produce "designer breeds."
I feel that this last point applies very much to the topic at hand.
I really don't see much reason to breed cross-locales, in my opinion there is such an incredible variety of Panthers out there that there isn't a reason to. If people do still do it (as they will) I think it's important to keep very close track of what bloodlines are in the animal, so people buying the offspring know.
I agree with Sang, the only reason I would see crossing locales as acceptable is if you were bringing out a trait (ex. if a transleucent gene showed up in animals of two separate locales) it wouldn't be hard to justify breeding the pair.