I have been using a ZE for the last 4-5 years. Not a problem with it from a mechanical perspective.

The only issue I ever had with it was when I had it on my old bow, the AR31. It had a big brace height and didn't allow for enough lift to get fixed broadheads to clear the rest area on the bow. I switched to mechanicals and it worked fine. This was a problem with the bow, not the ZE. We made all the adjustments on the ZE and couldn't get it to work perfectly.

I just bought a Switchback and put the ZE on that as well.