As an Office 365 subscriber, you currently get 5x1TB of OneDrive storage for $9.99/month (on top of the right to install Microsoft Office on 5 devices + tablets)
Microsoft is now upgrading that 1TB storage to...UNLIMITED STORAGE!
https://blog.onedrive.com/office-365-on ... d-storage/I don't think there's any competition to that in the market right now - especially if you need Microsoft Office anyway. What about that for a NAS backup?
Synology currently has OneDrive sync support implemented in DSM 5.1. It's not a perfect implementation yet, but it is there.
Please tell me that you'll implement this in ADM, and I'll ditch my home-brew xpenlogy box right away for an Asustor!
P.S
When (not if

) you implement it - please make sure it's possible to sync the root of the filesystem and not just a subfolder (as implemented in DSM)
D.S