I don't think it would be a kilt faux-pas to wear another tartan that you like. There are some that are restricted and maybe someone could make life difficult for you but all others are fair game. We all have worn a shirt or tie or pajamas in someone's tartan other than our own. I think that you make a point when you say it would irritate you for someone else to do it. Nice designs are often best seen on others.

I love to see lots of tartans. It is one of the things that I enjoy about going to highland games. I, like you, am drawn pretty much to my kin's designs. If you see good deals though, maybe you should collect some additional items. You may find your opinions and feelings change concerning cross-pollination of tartan tastes.