A leather PC? With a kilt on my harley maybe? I just don't think it would work. Now a toned down piper's doublet would be of interest to the RenFaire crowd, I'd bet.
Personally the idea of a tweed style jacket in leather or brushed denim doesn't strike me as bad at all. Strictly casual day wear but I could see it getting a lot of use.
Not being one that wears a glengarry I can't really post an opinion on that idea.

Mike