On a Prima you get less choices than you do on a Z. And IIRC the starting price for Prima Artists is now north of $15k, quite the gap from a loaded Z.
I can relate a bit to the concerns here, but, working both with John Fox and Jason @ Fret Nation, at least with those two dealers, it's a non-issue IMO.
My Red/Blue Z went through several rounds of emails between dealer, Dingwall, and myself to nail it down before finalizing the build spec. Then, when the bass was finished, I was given photos of it and asked to approve it or not. It was not to my liking, so, I worked with everyone on the rebuild. That unfortunately meant picking a new top as well. Couple weeks later, I got to see just the new neck by itself, and with that it wasn't quite what I had wanted, so we once more pivoted with try number 3. I was feeling kind of bad at this point, knowing that basically Dingwall has built 2 basses "for me" / my order. Picked a third new top at this point, which, to be honest, worked out as I liked it the best of everything so far. And I also got to have one of the first Zs with the Obsidian Maple freboard wood, which also is really cool to have!
So, even though it ended up taking a couple extra months, it worked out just fine and I have no disappointment at all with how it turned out in the end.