i've seen a few snap shackle setups which look nice, but won't work when needet - like twisted release grips and stuff - when you attach such a setup to your equipment, always try it a) under pressure - with the kite powered up in a typical situation (it is nice, when your system works with the rope you tied to a door-handle, but that won't grant it will work with a kite pulling twice your weight at a whole different angle).
and even more important: TRAIN IT! you can somehow wiggle out of the hooked center or chickenloop, but a shackle wont open just because you pull the bar and move your hips in panic.
it's a MUST that you learn the exact position and pull-direction of your release, 'cause in most emergency cases there's no time for reading the manual and try how it opens - it's more like: you got time for one grip and pull and then you're f***ed up.
so don't rely on a system that won't help you because you're not used to it.
and always remember:
when you are in the situation when you need it, you won't be as cool as usual, cause you're pulling to save your tiny a**. so the movement must be saved deep down in the motion center of your kite-polluted brains