R. A.
It's too bad that your "Frau" feels as she does. To me, a classical concert is an ideal setting to wear the kilt. She's right that it may draw attention, but I would only think that it'd be before the show when arriving at the venue and after when you're leaving. You could make the point that once you're seated no one except the people seated beside you will even notice the kilt. Anyway, these are the points I'd use if I had to make an argument for the kilt.

Will