@avatar1024 A lot of the same thought process as here, on block vs file sync.
https://www.enterprisestorageforum.com/storage-networking/nas-vs.-san-differences-and-use-cases.html
"SANs are the higher performers for environments that need high-speed traffic such as high transaction databases and ecommerce websites. NAS generally has lower throughput and higher latency because of its slower file system layer, but high-speed networks can make up for performance losses within NAS."
Here is the thing, Nextcloud is half baked on just about everything outside of file sync. I'd be VERY wary to trust it to handle external syncing. It might be easy to setup, but you're betting on their external storage plugin working as advertised under all conditions.
An interesting idea to be sure!