I have no experience with the Z3 but the loopy I have a few of and my experience is it can move, I luckily mark mine and check it everyday. Was hunting and noticed it was off a good bit so I just adjusted it back and it didn’t do it again. It’s only happened once in 3 years tho but it can happen.
I have them both and the Z3 is superior optically. I just acquired a VX3i with ZL and like the positive locking but I notice as I turned the dial the hash marks never line up so it may get sent down the road before I even mount it.
I've had both, The swarovski had better glass but I got rid of it because of the Reticle, I had the BRH and just wasn't a fan of it. I don't like generic BDC reticles on SFP hunting scopes.
BRH reticle is actually a mill based for elevation. The dots are 1 mil apart with half mil harsh marks in between. You can have probably any ballistic app calculate adjustments in mils for your load. It is a more usable reticle than any ballistic one imho
The Z3 is much better than the VX3i in my humble opinion. I've had several of each. For 500 yds and under, the swaro app is spot on for the BRH reticle