When faced with the same option, after much back and forth, we just decided to go with a 4 Bah stand alone NAS... build cost was really not an issue, but the T, E & AC (time, effort and associated costs) of maintaining another box was the deciding factor. Recently however, we have even dropped that. Just added two SSHDs to a CAD workstation and set them up in RAID to serve as office data server ... minimal cost, no additional admin, and 0 impact on file access (5 desktops / 5 laptops) on the system. After 3 months tho ... broke the RAID 1 and just set up one as the primary drive and the other as a secondary backup. Initially had the system mirror the primary to secondary twice a day (free FBackup) , but now just once. Drive is partitioned with each partition having permitted access by certain personnel. Also a HD Docking bay with a 3rd and 4th SSHD swapped out for off-site storage weekly. Nightly backups take about 30 seconds to 2 minutes, weekly off site < 5 minutes.