Gocard,
I agree with Silver, not to rotate a worn rear tire up front- I rotate when the rear just begins to show wear, not when worn, to clarify. I would rotate out a worn rear, put the front on the back and get a new front IF I wanted to stick with that brand/model tire. Which I wasn't about to do as I hadn't found the tires I wanted to stay with yet.

As for the wirebead vs kevlar, the wirebead is harder to take off, and will keep its round shape off of the bike. Those are the ones you see on a rack at the LBS, they can't be folded up and put in a box. Kevlar bead tires can be folded easily. They also weigh less.

I've been riding the road bike a lot this last month, and I'm liking those GP4000 25c tires more and more. They still look just about new. No cuts or visible wear. They ride really nice. I made the mistake of riding sew-up tires all through the 80s and 90s, as clincher tires weren't as advanced as they are now (19c tires were all the rage at one point and they rode like they were made of solid rubber). So everything I ride I subconsciously compare to cotton sewups, not a fair comparison. I wonder what the tires that cost me 80 bucks in the early 90s sell for now...