Here's my two cents: I recently was going to wear a kilt to a Friend's wedding, but i didn't. My rationale was that it was a semi-formal wedding, out-of-doors. Although it would have been fun, I felt that compared to the wedding party, I would have stuck out quite a bit.

In the end. I felt I made the right choice because the wedding party wore nice tuxes with tevas (the bride and groom were river guides, what can I say?). I would have indeed stuck out and I think it would have detracted from the wedding party, who should be the main event of the day after all.

All of this is to say that perhaps you should feel out what the style of wedding will be, what the reception will be like etc. etc. I know, it's a pain, but don't forget that it's the Bride and Groom's show, not anyone else's.