I think the captiv has some value fir devices that you can leave the carabiner in, but you need a loose connection for the device or parts to move. The Taz lov3, Petzl I'D and Skylotec Sirius come to mind. For permanent connections for devices like a Zigzag, Akimbo, positioner, etc. you could make your own rubber keepers, what I found best is bicycle tubing, either as a small loop, twist it once and it keeps anything well oriented, or more elegant is to use thicker walled tubing, and punch two holes in a flat piece. I prefer wire eye carabiners though, because it's easy to use it somewhere else spontaneously, and I also have a captive bar biner that I have on my positioner.