Really? I used to shoot off the string without a peep aligner. Good strings should not move once they are set in. Once the string has been shot in and settled all you need to do is play with the twists in the string until the peep lines up at full draw. With any of the current quality strings on the market they shouldn't stretch after that and your peep will rotate to the same spot everytime.

Now to the original question. Metal vrs String. I have used both, I had an Ultra Nock (still have it actually) for a while. I did not experience any of the problems most seem to be concerned with. It didn't damage my string, it didn't slap my hand and it didn't come loose and kill anyone. It does rob you of some speed though becuase they are pretty heavy.

That being said I prefer the string loop now. It pretty much does the same exact thing, except it's easier to install (once you know what your doing), easier to adjust, lighter and much cheaper. The metal ones with the tiny screws are a pain to put on and adjust.

Oh, and not all releases will work with the metal loops. I used a special release that had hardened rollers on the jaws (Rolleraid) with my metal loop. With a normal caliper release they tend to either chew up the jaws on the release or the metal on the nock. Or your release may not even fit in it.

String loops are just easier and more versitile in my opinion.

Paul