[fewayne]

I am aware of four quick-release/engage camera clip systems, two each from two companies: Peak Design offers the Capture and Capture Pro, Spider has its eponymous holster and the Black Widow. I have had hands-on with only one, but did some studying.

1. Firsthand experience: The $80 Capture Pro completely rocks. Built bombproof with a positive locking system, it's versatile, light, compact, excellent ergonomics, fits quick-release tripod heads, holds the camera very securely.
2. The $49 Capture looks to be rather nice but not as overengineered. As rough as I am on gear, I wanted bulletproof.
3. The $65 Black Widow looks to share the advantages and drawbacks of the Spider, again not as overbuilt.
4. The $135 Spider looks even more heavily engineered than the Capture Pro, and doesn't care about the camera's orientation when holstering -- get the pin in the slot, and you're done. I did not like the $50 price premium, nor how the camera can swing around when holstered, nor the necessity to add an extra plate to allow tripod use, nor its unsuitability for use as anything but a hip holster.

For me, the Capture Pro was the obvious winner.

• Its camera plate fits ARCA quick-release tripod heads -- an alternative plate fits those as well as Manfrotto ones. No extra thing to attach. (Minor quibble: you can set a camera down on the plate and it rests, stable; with a pin sticking out it I think it would tip.)
• When holstered, the camera is securely held and can only swing insofar as the strap it's riding on twists.
• The clip can go on all sorts of different straps, and works very well on a belt at your hip or on a backpack strap, adequately on a camera-bag strap. (The clip can also screw onto conventional 1/4" tripod heads -- presto, instant quick-release system on any tripod!)
• The clip has not one but two positive locking systems -- one locks the release button, and the other mechanically traps the plate in the clip. Clearly intended for very active use.
• You can choose the orientation in which the camera clicks into the clip. I usually point the lens down, but can rotate it 180 on my belt or 90 on my pack-strap so that I can see the lens mount; you could also face it forward for literal from-the-hip shooting.
• "See the lens mount" -- there's a reason I mentioned that, namely that when clipped in, the body is held rigidly enough that I don't have to hold onto it to change lenses! That means I have one hand devoted to each lens and am HUGELY less likely to drop one -- or, alternatively, can do it one-handed, and can hold onto a boat or a railing or a ladder or rock ledge or whatever. For what I do, that's a big, big win! Same goes for fiddling with settings, I can click it in so that I can see the screen and access the controls if I want, one-handed, whereas the Spider shows you only the bottom of the camera.

Now, before you arachnophiles eight-leg it all over me and bite me with poisonous mouthparts, I am NOT dissing any of these four products. Rather, I seek to elucidate what sort of mission the Capture and Spider are each suited for. Prefer the Spider, IMHO, if instant holstering is very important and you're not as worried about things banging around, or using a tripod. For example I imagine it would be even better than the Capture for weddings, or similar events in a tamer environment, and when you're always using it in pretty much the same way (belted at your hip). I'm much more likely to be hiking, or skiing, or biking, so I got the product better-suited for that.

Finally...bewaaare the video! Peak Design has an EXTREMELY seductive little video that will make any self-respecting gearhead drool. I still haven't gotten their little string-quartet tune out of my head! Two caveats:

1. While my Capture Pro engages positively with an audible click, it does not make the seductive, lush little "schnick" noise that was Foleyed into the video. I was crushed.
2. Having gone walkabout with the thing on my waist, I can now see why the video featured people who are much younger, more attractive, and a helluva lot slimmer than me. For one thing, of course you want to be like these young hip outdoorsy people -- buy a Capture! For another: Huh, I bet all those people can actually see the clip on their belts when they're clipping in the camera...

[marmitse]

I can only add to the Capture praise. I got the Capture version 1 last summer and have been using it for hiking, climbing and biking since. I use it both on the back-pack strap and on-hip on my belt, typically with my K-5 (Now K-3!) and with the Pentax 18-135/3.5-5.6 attached. It works very well and has not shown any wear. Great thing is that it also fits with my Manfrotto tripod plates.

Version 1 was a bit crude in the finish with a few sharp edges. The new Capture pro looks great and have likely fixed this.

I attach a photo from top of Norways highest glacier Glittertind (sorry for low IQ, but the pic was taken in strong wind and with a cell-phone cam). The Capture & Pentax K-5 is on my left backpack strap.

[kain]

I have become a real sucker for capture plates + benro arca-swiss type ballheads myself.

[Tsuken]

I used my Capture for the first time yesterday, at an Easter funday for the kids. It was absolutely brilliant. Comfortable, convenient, easy - and yes: very cool. ;-) Had an Olympus user come up and ask me about it.

[derekkite]

I'm impressed by the Peak Design products. I got the leash and cuff a while ago and use the leash all the time, got a second one for my second body. The cuff they sent me was too small to get my hand through, but they fixed it and are sending a replacement.

Got the Capture pro bundle a short while ago and have used it a couple of times. Works very well. I had my K-3 with 100mm macro and ring flash hanging on it, with the pro pad. It just worked. I had the leash around my neck for security, but after a while I didn't even notice that I had it on. I was also carrying my second K-3 with DA*300 on a tripod on the leash. Quite a load, but it was secure, comfortable and both bodies/lenses were ready to use quickly.

Very impressed, and I'd suggest anyone to take a look. Prices are reasonable, and the stuff works.

[link81]

I've been eyeballing it for a while. Now I think I'm going to pick one up for my q, and use a regular strap for the k-30

[mtux]

Recently I bought their professional pack bundle. and am very happy about it.
But I didn't check other systems.

For some time I was just unhappy about my K-30's strap, it was too short to use as sling, and too big.
So the Peak design leash (sling strap) is perfect for me because:
1) it is easily detachable when you don't like having a long strap wobble around your hand/neck (specially indoor where it's safe and you are sure you won't drop the camera)
2) it's easily resizable and I'm able to make it long enough and keep the camera easily on my side. (when I'm not wearing the Capture part) one thing wasn't possible with K-30's strap.

I also love the Capture because:
1) it freed my hands during my previous trip while walking in jungle and beaches, so I could move around easily while carrying my tripod.
2) And I was able to change my lens very conveniently while my feet were inside sea waters and there were no place to put down anything.

P.S: this was my answer to Rod, which requested my opinion on the sling strap, I thought it might be helpful for others too.