Nope more or less anyone who has tried USB Sata for Raid unless a pseudo raid such as snapraid will tell you its a pretty awful experience.
JMB585 should be fine but you are still stuck with the Rockchip BSP kernel.
What NAS/SATA for Rock 5 did is a great example and you can get simple low cost acrylic towers where the disks themselves create the structure.
Rock5 would make a great NAS but so would the Rock3, but just a shame it got that Pi format as its images are new but definately more mature.
I would let others trail blaze a path 1st.
PS Cockpit has some great interfaces for Samba/NFS