I would go back if it was easy. The speed difference from just getting a listing of contents in a large directory over SMB is insane. It used to be instant and it takes like 10-15 seconds now. I'm not even using their app setup anymore, I gave up on it after a while because of a bunch of random issues with updates over time and switched to a dedicated box with Portainer installed. I really wish I could go back to core.
I'm sure they'll iron everything out but BSD is still king at the moment.
Check out Kavita! It sounds perfect for what you're doing and I have had literally 0 issues using all of their built-in features. It's a surprisingly stable and full-fledged open-source product.