I purchased the HED Jet RC4 Black wheels last month and mounted Conti 25mm GP5000s on them. I ride a carbon Pinarello F, and the combination of the wheels and my frame feel like a dream bike that was custom made for me. After 350 miles here are my thoughts. The "feel" is the first thing I noticed. I inflated my tires to HED's very specific PSI from their website's inflation table, and it literally felt like I was riding on clouds, or for other hockey players or ice skaters, it feels like a fresh sheet of ice. The feel is immediate, and really nice: it's as if you're riding in a ultra luxury car with premium suspension. The HED wheels are on the expensive side, but you really do get what you pay for. I have picked up a couple of tenths of MPH average on my Garmin, but that could be due to any number of factors (cooler temperatures lately/fast riding groups). The rim brake stopping distance is really impressive. I haven't had to test them in wet conditions, and honestly don't plan on riding in the rain. The quality control from HED's manufaturing site is pretty solid, as there are so many Q.C. signatures on small stickers inside the rim. I am really happy with this purchase, and truly hope my experience with the Jet Black RC4s stays this way.