I was reading through this and tried to picture what was being worn. Though I would ask, is your kilt a dark tweed, maybe with no psttern, or a black kilt with pockets, or a plain wool kilt, that's just black. In my mind I cant picture a tartan plaid not looking off in either. I guess it would also depend on the event as well. Not many cases a plaid would be worn, pipers, your wedding etc.