I'm currently riding a set of Cosmos and when it's time to replace them I plan to do so with an Ultegra/Open Pro wheelset. If the two sets were the same price I'd recommend the Ultegra/Open Pros. As I said before tho, I like the Cosmos. I've treated them rough (potholes, jumping curbs, little dirt here and there) and they've held up. They have a really small flat spot now tho. I can't notice it riding, but I can see it in the truing stand and it's there to stay. I hit a pothole at about 30mph. I got the front wheel over it, but the rear wheel smacked hard. The pinch flat was 4 holes, one on each side of the rim and both sides (rim and tire) of the tube. I learned a good lesson tho... don't follow too closely on curvy, fast, rough roads.