I'm glad you got your FTP solution working. Congratulations!
Our tests were a little different, as I was testing for CPU consumption in isolation from storage.
- With that tiny CPU in my receiving server, SSH authentication and decryption was three times slower than plaintext. I will continue to use sftp(1)/scp(1) for file transfers because of its operational ease compared to other file transfer methods.
- An NFS solution might be something for you to consider, depending on your specific needs for file sharing between systems. OpenBSD's implementation consists of a fully-integrated client built-in to mount(8)/mount_nfs(8)/fstab(5). For an OpenBSD-based NFS server, there is a small set of daemons, with provisioning guidance in the FAQ.