I've been using these tubes now for about 2 years. They are light and no less reliable than any other butyl tube I've run. They are also quite compact and I can fit 3 of these where only 2 would fit of a bulkier tube. When on sale the value is good.
After ordering these tubes I did lots of reading about how lightweight race tubes are horribly unreliable & require daily inflation. Nothing could be more untrue about these contis I got them as a set with Ultra Sport II Folding tires & I ride every day. The rim has bottoms out sometimes twice a day, and I dread a pinch flat each time it happens, but so far the tubes have held up lovely. I've begun stocking up on tubes & conti tires bc I think they have the best product & reputation in the sector.
Over the years I've tried many different brands of tubes and tube materials. Found the Continental Race Light Road Tube to be the best value for durability, weight and ease of patching should the need arise with multiple flats, caused by road debris, while out on a long ride.
I am using my Race Light tubes with the Conti Grand Prix 4-season Vectran tire on Shimano RS-11 rims. This is not a particularly light weight set up, nor is it fragile. The tubes are well protected so I am not worried about damaging them.
This tube is nice middle weight folds up neatly doesn't weight much & isn't fragile when putting in when standing on the side of the road wishing you could hurry up and not be standing on the side of the road go ride!!
Been using this tube for years mostly with Vittoria Rubino Pro's with a fairly high PSI (110-120). I get pretty good milage out of these on my road bike, commuter bike, and track bike.