The butyl isn't the lightest but it's pretty sturdy for daily use and I don't have to fuss with valve extenders on my carbon wheels. I like that they are pretty durable and have smooth valve stems so my pump doesn't get chewed up. They hold air well and last quite a long time for me.
I just received a replacement Michelin A1 Airstop Tube from WesternBikeWorks due to a faulty valve right out of the box! The tube was replaced with just a note to WesternBikeWorks, thank you! I ride 3-5x a week on flat to rolling terrain, usually pavement or concrete, so not a lot of stress on the tires. I rode the bike about 10 miles last night and parked the bike on an indoor lanai. About an hour later I heard something like a gun shot out back, not a gun shot though. The Michelin A1 Airstop Tube on the back wheel exploded! So keep the old tubes, you may need to replace the Michelin A1 Airstop Tube sooner than later. May be a QC problem at Michelon, don't know, this never happened to me before.
I had a lot of bad luck with the tubes I was getting from my local bike shop and decided I needed to find something more reliable. I did a bit of research and chose to try out this tube-it was well-regarded and came at a price that made it worth the trial. Good thing I ordered them, a couple days after they arrived, I had a flat and needed to put one on. Since then I haven't had any issues. They hold pressure pretty well and they're lightweight. I like the smooth valve, too. It seems to work better with various pumps. I plan to use this tube from now on.
I use these tubes on three road and two adventure bikes and have had no flats with literally thousands of miles of use. The french valve has thick rubber on the base of the stem inside the rim which is conical shaped and has eliminated the annoying tube cuts at the valve.
First tube I tried on my rear tire on my Road Race Bike blew after cycling only 1 1/2 miles. I was angry seeing I was on my way to an appointment. The send tube I'm on seems to be holding air after 2 days of use.
I won't purchase this type of Michelin since the first one blew under 2 miles of cycling. I inspect the whole inside of the tire and notice no kind of puncture. Only switched to this tube because it was cheaper.
I'm going back to the Michelin UL 700 x 18-23 52MM PV. I'll spend the extra Dollars for a lasting inner tube.
I'm a Serious cyclist since March 2011 using my bicycle as my main transportation.