This isnt going to be an easy decision, because I brought a black CP Sling blade trigger for the ion. And i thought it was a beautiful trigger.
But that was around 3 years ago, so maybe the quality of their products have decreased somewhat.
I also have brought a NDZ roller blade trigger. And this was another beautiful trigger, if not better than my CP.
So the main difference I found, was that the CP triggers tend to use springs, whereas NDZ triggers use magnets.
Overall I think I would go with A NDZ (New Designz) Trigger - Just to be safe.