I happen to have an OG Auteur and an Auteur Classic here at the same time.
Actually, I had both of them here for ABing before the CanJam Chicago 2022 preview video, and my comments therein are based directly on my comparative listening sessions between them. At the risk of possibly being unhelpful, I've specifically avoided talking about them too much since, as I was hoping for more people to chime in with their own comparisons.
That said, I've just now realized that the best comparative impressions may not come from those of us who upgrade, but from those of us who eventually wind up owning both... which probably explains the lack of such impressions.
EDIT: Oops, posted this too soon.
In any case, I'm happy to answer any questions regarding sonic differences that I can. Just one caveat, I'm in the midst of working on the CanJam London preview video and auditioning gear for those video segments, so I may not be able to respond super quickly. But I'll try my best.