I feel pretty good about them based on Z1's rep. I have a lot of their stuff on my Z, not a problem with anything, and their customer service is great. I'll be going with the race version, my car doesn't see the street very much, mostly track. Maybe I'll be first, it will be a couple weeks...
Adjustment... It looks to me that the points that connect to the chassis are the caster adjustment and would have to be spun to adjust. You would most likely be able to figure that out before install. The other single end would be your camber adjustment. It's not very hard to un-bolt and spin this part. Best part about the way they adjust is they won't slip. Once you get them set it would only be toe adjustment for re-alignment in the future.
I am really stoked to see Z1 make these. I'm running the OEM ones now. I had a set of AMS that didn't work out, bushings too soft. Don't want SPC, and don't really wanna pay $800 for SPL that I hear seem to loosen easily on their own. Nothing against SPL, I have their stuff and it's great. I would have bought SPL A-arms at some point, just would feel like I had to check them all the time.
...And for $300
Z1