Works absolutely great with my ATC guide. Keeps everything where it should be, with no crossloading or any other shennanigans you encounter with a regular biner. Takes a bit of getting used to getting it on and off the belay loop, but works super well. I actually notice that when my climbing partner is hanging and the full weight is on my harness, it pulls evenly on the leg loops, so it doesn't get too uncomfortable! It also helps to keep my ATC feeding rope nice and smooth.