I currently use immich with 40k+ files.

I think what OP meant by 'early development' is the updates with break Changes.

Ive been using immich in docker self hosted for 1.5 years.

I use authentik for user management and single sign on.

The breaking changes have only ever been minor changes I've had to make to my docker compose file, its always come back with no issues after the well described changes in the release notes and several of the changes I didn't even have to do because it did not apply to me.

This is petty standard stuff for anyone used to self hosting but if that sounds like its not for you then check out the roadmap. The stable version is expected next year sometime. Wait for that before giving it a try.

https://immich.app/roadmap/

Personally I like the fast development, I find myself likely and using at least 1 new feature ever major update. I think this will easily become the best photo manager in 1 to 2 years and it will not longer be much of a competition