I would think Regency!Mal is definitely a bit more polite because it's the norm in those days. If he weren't a ship's Captain, he'd probably end up being of those handsome & rakish gentlemen always found in the men's clubs and possibly has a penchant for playing cards (in addition to more gentlemanly pursuits).
Re: Firefly: Wash and Mal
... of course, he could also be both. :-)