[MC5C]

I guess my answers would be - yes, I would expect some early (first 6 months or so) movement in a neck, primarily because I see that in every guitar I build. So I think it's completely normal. Second, I think a reinforced neck can be quite stable over time - I have a 1957 Hofner that had a fingerboard plane and fret job 30 years ago, and it's only now starting to think about wanting a light fret dress over the fingerboard extension (archtop, floating extension). Third, the neck is made of wood. Wood, even with a stiffener, is not a particularly stable material in the greater scheme of things. Expecting a piece of wood 20" long to hold .005" is a pretty big ask, yet somehow it usually works out.

I would personally not assume that it's done moving, and would take small steps. If you want to get from .010" to a more reasonable .005", I would start with a simple fret dress. Take the high frets down a few thou, and get it happily playable, and play it for another 6 months. See what it does. Then decide if that is acceptable. Make another decision then, having not done anything that isn't reversible. Given the compressibility and movement inherent in wood, I'm not a fan of trying to force the wood into a place it really doesn't want to be with oversize frets. It will just move back over probably quite a small period of time.

Just my opinion...