Maybe I shouldn't have been quite so optimistic in my notion of when sculpted prims will be ready for prime time.
The 1.16.0 beta client, which supports said prims, is out. I've downloaded it, set up a launcher for it, run it... and watched it crash immediately when it started to actually display where I was.
There was an update, and I have grabbed it. It gets far enough that I can see the fade from the "where were you last time" image into wherever I am on the beta grid... and then it crashes.
I'm hoping such a blatant bug will be an obvious goof-up, and things will improve quickly.