Tried one for a bit... went back to regular tubes. My experience with them is that the wheel never felt balanced, and when I did run over a nail, the tube didn't seal. The goop made it more annoying to change the tire, and maybe a bit slower because... well, its slime, and I'm not accustomed to leaving slime on my hands. So I'm back to a plain ole 700x32 which I can change in just a few minutes on the road with a tube that costs 1/3rd as much, is easy to patch, and doesn't have a weird wobble to it.

Now... maybe all my problems with them could be chalked up to "operator error", not sure, but none the less, the experience was less than desirable, and I won't be buying another.

nb.. I to have puncture "prevention" liners in my tires; not really convinced they do as described, but they don't seem to harm anything and maybe they work.