I don't think it's really that big a problem, it is a fairly recent development all this matching tartan, so really a non issue if you ask me. Now would I do it? I'm not sure however he may be able to pull it off. A question that comes to mind is this what are the other male participants going to be wearing? If for example you and your best man etc. are wearing the Prince Charlie then would not he be expected to wear the same? It is after all your wedding.