I got these this year since I've started racing as well as doing more high climb centuries (9000 - 11,000 ft) to save weight. However, I'm switching back to Tour 700s because I've been having so many pinch flats during training rides. The rural roads around here have plenty of potholes, rocks, debris, etc. and I got stranded 50 miles from home yesterday with two pinch flats (one on my rear tire and then another on my spare).
Have used these Continental Race light tubes in 700x25 (Michelin) racing and training tires for several years. No problems. Stems work well with screw-on, shop and bike-mounted, pumps (Lezyne.) Sometimes I deflate slightly after ride, sometimes I just leave them at 110 psi. Doesn't seem to make any difference. (Although I still feel, from the old sew-days, that stretched rubber should be allowed to rest after a ride.) I would give it 5-stars except can't see calling any plain-ol' bike tube awesome and a steal. ,-
I purchased 2 of these tubes. 1 burst at only .66 miles into my ride and sounded like a firecracker! Seam split. The other held up for the ride but I may remove it. They leak air like crazy 20lbs over night. I will not buy these again.