Thanks for more input guys.
Every time I mention to people that I'm wearing a tweed jacket to a wedding they say "that's not formal enough". I tell them I shouldnt really wear a Prince Charlie since it's too formal as I have no role in the wedding and I'm just a cousin as well as the time of the wedding being very early. They seem to think that tweed jackets are for OLD MEN and JUST FOR HUNTING... (obviously they don't know you guys!)

I think I'll wear a black Argyll to the wedding simply because I want to wear a cravat and it doesn't really go with the tweed... I'd also feel obligated to get a brownish sporran to go with my jacket if I were to wear the tweed.