I heard about these from some competitive cyclist friends. I saw one at Columbia and talked to the owner. I read the favorable reviews. So I bit. I ordered one today.
What, a $1675 disk wheel? Good grief, no, that's almost what I paid for my whole bike.
No, a $60 wheel cover. Heck, that's less than I paid for my cool new competition tri-top (which was worth every cent - it performed fabulously well throughout the day yesterday even though it's a bit too tight yet).
If wheel covers help boost my speed at Eagleman in combination with my geeky aero helmet, even if the effect is only psychological, they will be worth it.