My experience with Zipps:
Late fall 1994, I grabbed a used set of 404's in tubie on ebay for the absurdly low price of $650. Included an extra pair of tires. Just wanted to try them out, and figured that I could sell them for at least that in the spring.
I still have them. Just hate to take them off the bike. The combination of light weight, fast speed on the downhills, and damping of road vibration make them a delight to ride. The tubular tires have proven most resiliant. I've had only one flat, and it was my fault for taking a shortcut down a debris strewn street. Probably put 1.5k miles on them last year, no durability problems. I did have to do some minor truing twice. I can't say enough good about the 404's. They just feel fantastic.
However... the Zipps are a lightweight wheel, and they can be fragile. Do you really want to hit a pothole with a $1500 wheelset that's optimized for weight? Not really for every day. When I'm riding anywhere but smooth, well maintained back roads, I put on my old Rolf Vector Pro's. Harsh riding, but they're tough. Keep in mind that the extra money the high dollar wheelsets cost buys you speed. It does not buy you toughness.
Just my opinion, but why spend all that money on a light wheelset, and then burden it down with a big chunk of aluminum? The tubular rims are lighter, and tubies really aren't that much of a hassle. If you're going to go light, then go all the way.