Been using them for years, mostly made by Tom A. http://rapidwinder.com/
A few thoughts: love them as they give me an extra stop. Don't use them on a Leica M7 as they can displace the shutter post if they get caught on something. Never had this problem on any other camera. The full size soft release fits beautifully on a Leica body, but my experience is that they can get bumped easily thereby taking a wasted exposure. So I use Tom A.'s mini soft release for my bodies that have a threaded shutter button. I love the milling on Tom A.'s. Gives a good grip. Sorry if I sound like a Tom A. fanboy as I am.