I just used my Williams 58 Tubulars for the first time over the weekend. I can't say that I noticed a difference in top-end speed over my Ultegra SL wheelset. They are stiffer and acceleration seems a tad faster than the Ultegras though. I bought mine used for ~$450 and I am happy with them so far for that price. I can't imagine that any wheels are worth $2000 and I only think I would be seriously underwhelmed by such a purchase.