For what it’s worth, NFS in my experience is also faster. I had a very similar use case (but QNAP instead of Sinology) and switched everything over to NFS and saw performance gain. Little things like previewing IP Camera security footage would feel slow on SMB, but snappier on NFS. I’d gotten over the user thing, but the speed is why I switched.
I did eventually wipe QNAP’s software in favor of stock Debian – but the prevailing wisdom seems to say Sinology’s OS is pretty good.