Nope, I've not used one yet, but all the inflatable mats on the market are waterproof, so I don't think that's an issue. I sat on a couple and they feel just like any other self-inflating mat.
Therm-a-Rests and the Insulmats that Mountain Equipment sell both use die-cut foam with cavities in to cut weight, the Ortlieb one doesn't and that, combined with the bombproof material, is going to push the weight up.
Then again, the UltraLight Therm-a-Rests, in my experience, tend to puncture a little too easily. If you're intending to do a lot of bivvying on sharp, rocky ground then the Ortlieb makes sense, if it's mainly to be used in a tent, then probably not in my reckoning anyway.
Posted: 08/08/2003 at 10:33