I've used them for a couple of years now fishing for cats with a slip float rig - haven't tried limb lines or noodles. I like them because most hookups are right where they're supposed to be - in the lip or corner of the mouth. I've had very few come off and I'm convinced that was because I yanked too hard setting the hook. I don't think I've ever lost one when I just reeled the slack out of the line and gave just a tug to set the hook.
They make hook removal a snap. Use as small a hook as you can to prevent hooking small cats through the eye (if you'll release them). I've even made small circle hooks for bluegill fishing with bait by bending J-hooks with pliers. They work for them too, and it's better than killing a bunch of little bream that swallow the hook. Small ones are available, but I'm too stingy to buy them until I use up hooks I have on hand.