I haven't tried any other systems out there, but I have been using the Capture Clip for 6 or 7 months now. It's great and I love it.
My 7D was always a bit too heavy for my camera strap-- and after I got my 5D, I haven't even bothered taking the Canon strap out of the plastic as I've been using the Capture Clip this whole time. It's great for hiking when I can hang it off of my backpack strap. It holds it in secure, yet I can pop off my camera quickly when I need to-- which means that I'm not missing pictures that I may have been too lazy to take if my camera was packed away or just too slow to drop my backpack and get my camera out.
The only real complaints I have about it are minor:
1) If your gear is heavy (5D +70-200) and attached to your belt, you will notice it. It pulls down pretty good, so you need to cinch your belt an extra hole.
2) When you do have a heavy set up on your belt, it tends to torque the capture clip and can push into your hip some depending on how you have it. It's annoying but not bad. However, for longer hikes it might be a problem. Although, for longer hikes I'd be carrying a backpack and have it on the shoulder strap strap. I do notice with V2 they are offering some sort of pad-- that may fix this issue.
Otherwise it's secure and I love it. If I were to buy version 2 now, I might spring for the one with a metal back just because that seems like it'd be more robust for hanging $5K of gear off of it. However, I can't see that tripod screw on the back ever being used. That's why I have an Arca swiss quick release plate, why would I use this clip for that?
So, long story short, if you're a hiker/biker or just traveling with a backpack and your camera on a fairly regular basis, get it. It's great to have your camera right there on your shoulder strap. And, really, even if you aren't toting a backpack around, it's great to have the camera clipped on your belt, especially when changing lenses-- it's a stable 3rd hand to help you out while you're juggling things around.
