I would say that a Prince Charlie would be far too formal as a guest at a wedding. Remember that the Prince Charlie is akin to a Tuxedo, so ask yourself would I wear a tuxedo to a wedding if I were a guest? My answer would be no. Therefore if I were going to wear a kilt to a wedding I would do so with an Argyll or Braemer jacket as these are more in-line with a suit, in this way you will blend in much more with the other guests.