I'm happy with the purchase. To me, it was worth the cost.
I've had more than one instance where I needed to get the bike back together quickly and was getting very frustrated with the caliper bracket and the wheel spacers falling out of alignment. I'm talking about racing and track days. For street use, where a tire lasts for a month or more, I don't think it's worthwhile. If you regularly ride on slicks and have to switch to DOT tires for a superstock class, it's worth it. If you race or do track days in the rain and keep a set rain tires handy, its worth it. If you don't normally change tires at the track, it's probably not worth the cost unless you get aggravated easily while changing your tires.