I think some other company tried marketing a similar product a few years back. I might use them for touring use but wouldn't race on them, and probably wouldn't trust them for mtn descents.
Normal sew-up mastic (contact cement) relies on an adhesive to adhesive bond. Dried layers of glue are established on both the rim and the tire base tape, and a final tacky layer is used to hold the tire in place. I wouldn't think one tacky surface would be sufficient to keep the tire from creeping or rolling off in more extreme circumstances.
Jon Schaer
Columbus, OH