I've tried them myself and didn't like them one bit. Total waste of money. Felt nothing like tubulars. I did, however, like the tubular clincher cross tires. Unfortunately, they don't make those anymore.

The cross tires, you could run with very, very low pressure and it wouldn't roll. As a matter of fact, it took me nearly an hour to just get them off the wheel. The road tires you're suppose to be able to run them at very high pressure and thus have them perform as good as tubulars. Not the case.