I should add that I did not mess up my the experimental design, unlike Jobst's unsupported contentions in the FAQ.
I used same inner tubes (patched twice) after installing tire savers. The tire involved was the front, not the rear, and my route to work was only about 20% on-road, and it was a backroad unlikely to be swept. I remember it was not cleaned right anytime soon after tire saver installation. The rest of my route was on bike paths or sidewalks which were not swept.
The reason tire savers are not sold today is that racing (and not touring) bikes have become the norm; tire savers add drag; round-the-world tours are less frequent; and manufacturers claim that kevlar belts work 'almost as well' as tire savers.
But if you think about it, only tire savers will heal an injured tire with a piece of glass or thorn that is working its way through the casing as you ride down the road. Kevlar can only last a little longer than traditional casing tire casing.
I suspect that Kevlar belts lead to more tire sales (one of the most significant profit-centers in cycling), and so that's why they are so heavily advertised as "stopping flat tires!"
- Don Gillies
San Diego, CA, USA