It maintains the impact point/scope zero as good as my Vets or my USFT (read PERFECTLY).
Up until last week it had the same scope zero for about a year, since I first got the .20 barrel. It was the same scope zero I'd used for sub20fpe field target all last year. And the only reason I changed it last week was b/c I was tired of utilizing hold UNDERS for the .20 NSA slugs when the hammer wheel was dialed up for them.
So, changed the scope zero to be 30 yards with the .20/18.9 NSA at 910-915 instead of the prior 30 yard zero for .20/13.73 @ 805fps. Shot it with the new zero in a couple sessions, verifying and acquiring dope data for 10-100 yards. This was all in prep for a Ultimate FT match this past Saturday. Realized on Friday night that I hadn't cleaned the barrel in quite a while, so pulled the barrel and disassembled the shroud to make a deep barrel clean easier. This was when I noticed the front centering oring is a bit stretched. Anyway, put it back together on Friday night and drove down to Phoenix and shot the match on Sat afternoon. My score was the second highest overall score (14 shooters), at 32-33fpe using 18.9grain slugs. The highest score was with 34grain slugs, at 980fps, for 72.5fpe. So, less than half the fpe....but I digress. The point I was trying to make is that the Ghost maintained its zero, even after a barrel pull, shroud disassembly, and then reassembly. And that's representative of my experience throughout the entire 19months I've been shooting it.
You mention the Evol Mini. I don't mean this as a comprehensive "EVOL versus Ghost" but generally, the EVOL is a very solid gun, doing what it does, and being completely reliable in that. The common comments about the EVOL not really being a tuner's or tinkerer's rifle seem accurate to me. Heck, I saw an ad recently for one BECAUSE the guy wanted a tinker/tuner gun. With the external adjustments and easy barrel swaps, the Ghost is much more of a chameleon than the EVOL. That doesn't make one of them "better" than the other, just different. Ghost is more apt to please a tinkerer/tuner. EVOL for the "set it and forget it" type of user.