Hi @tobihagemann ,
I tried the WebDAV Solution without Mountain Duck with an OneDrive for Business (Office365) cloud storage. (don’t mess it up with “normal” OneDrive). As most of you probably know OneDrive for Business is based on SharePoint architecture.
The connection is a hell. I spend hours to establish it, and at the end I saw no other option than use a PowerShell Script. Just connection a Network drive providing your login credentials? I was not able to realize it for hours and gave up.
After I managed to setup a complete automated backup process (running PowerShell Script to mount OneDrive-fB, auto unlock cryptomator vault, run backup) I notices, that the performance is so bad, its not usable.
I’m talking about 1 File Sync every 20-30 Seconds (Testfiles, not more than 1MB each, just compare operation, no upload).
My Backup has actually about 50k Files, so a backup sync process would run about 14 days (!).
I have no idea where the bottleneck is, but I guess its not cryptomator, as its encrypt/decrypt performance is really good.
This is just an experience report for other OneDirve-FB User.
Maybe the file-on-demand feature will solve this (unless cryptomator won’t have issues with that feature on roll-out 
)