The ScuttleButt is designed to be used with most leg-loops-and-waistbelt-style adjustable leg loop harness. Sleeves allow the leg loops to be slid into place. A gap in the sewing allows the holdup strap to be pulled through and used like regular. In the new version, the whole waistbelt slides into a fabric sleeve, with a gap at center for the back hold up straps to be reattached, though they are not needed. For the ScuttleButt to work, the leg loops of your harness must open fully, so they can be pulled through the sleeves.
Canyons involve a lot of sliding, scraping and general thrashing. Which ends up with a lot of scraping and thrashing of the gear and clothing upon which that sliding is done. The harness, the shorts, the wetsuit - they all get destroyed on a regular basis.
How Long will it Last? Hard to say. Depends. The seat is made of a medium-weight PVC boat fabric, and should be pretty good. I tried using a heavier fabric, but it was rather uncomfortable to walk around in. My experience is that it will last a while, and can be easily repaired or patched. I forsee a large amount of duct tape in the ScuttleButt's futures.