I have two UK, one Standard, one Mocker; plus 2 Amerikilts. Bought them all back in Sept '07. I don't wear them often, as I favor Tartans.
The UK's are still in great shape.
But one Amerikilt has shrunk, pleats all curled, so after only a few months is ready for the rag bag. The other Amerikilt is not too bad, but pleats do curl horribly.
The Utilikilts however, prove to be much more durable, and still look great.