[GeeTwo]

No, I haven't used the 3-stop model, but we have always done well with Bimba products. We made a 3-stop pneumatic setup for our Ultimate Ascent climber. The solution we came up with was remarkably light -- we used two equivalent double acting cylinders with double-end (X) mounts, and placed them side by side but pointing in opposite directions. We then cut two flat plates with two holes in each, placed them over the ends, and tightened down the four nuts. The picture attached shows about what it looked like. Because we didn't want our hook to rotate, we used a hex shaft on the free end cylinder and made a "cage" of angle aluminum to keep the free cylinder in the desired line; if you're not worried about the rotation, this could probably do it for you.