RE: Any opinions on the Ultra Nok? Do you use them? Hate Them? Opinions?
I've seen tons of strings break right at the very edge of those things. Think about it. The string has to make a hard angle around the metal at each end of the nockset. Once it has taken so many bends, just like a paper clip, it's gonna break. String loops let the string take a more gradual bend and don't cause nearly the damage as metal loops.
Not to mention that metal loops can gall and burr up the jaws on your release.
I've also seen metal loops peen the backside of arrow rests on low brace bows.
The ONLY plus I can think of is they are better at holding the peep in alignment at full draw. But even that plus is a negative, since it's putting at least some torque into the string.
Metal loops are not my cup of tea.