before magpul pulls the plug
If you are worried about which to get before the plug gets pulled, you should get both. You won't get the chance again if indeed the plug does get pulled. Better to have it and not need it than need it and not have it. You'll be kicking yourself later otherwise.
Betweeen the standard 1-1\4" standard mount or the HK loop type on a one-point sling
Personal preference coupled with training will determine which you use on a regular basis. However, unless you have both to train with, you won't know. So again, get both and decide after you have tried them both.
If you are counting on the H&K snap hook as a 'quick' means of detachment, think again. There is nothing quick at all about removing the hook under duress (sp?). A quick detach stub on the other hand is instant. Most single point slings now come standard with a quick detach point close to the receiver to detach the weapon from the sling in a hurry, leaving the stub attached to the weapon. Having a quick detach one inch from a hook seems unecessary and redundant to me. You can already detach from the weapon in a hurry, so the only reason to use a hook (IMHO) is if you are already setup with ring style sling mount. Even then, I would switch mounts before I used the H&K snap hook. I prefer the added stability of the standard webbing stub.
Contrary to my remarks above, the H&K snap hook does have its uses. It works well on smaller, lighter platforms like the UMP, AR pistol builds etc...
In the end, personal preference will dictate. Try them both and decide for yourself.