whilst climbing at the Moaning Tree my friend Cam C. had a double dinner plate occur and pitched backwards and down 20' onto a 17cm screw in very soft wet ice. the On sight screamer not only held, but only about the first 5cm of the stitching unwove.
i have 5 and use them all the time ice climbing; rarely alpine or trad climbing. i usually take along one, and only clip it to sketchy fixed pins of unknown age.
RPS themselves can act as load limiters. if you place 5 or 6 in a small distance (like 6 inches apart) in a thin crack and fall on them, the first 5 or so may rip out or break cables, but this will dissipate force and the 6th one will then catch you. i have only theoretical experience in this but it was well discussed in Mountain magazine c. 1978