Hi,
I have now also been testing the Bechfish client and it works perfectly except for the limitations they have sat for the length and some characters. But I am sure they fast can fix this and I have made the needed corrections for the files that did not sync. I used the app SharePrep on my PC to do the needed changes. This app scan your files and folders that you are going to upload to SharePoint and OneDrive for Business and do the needed changes. You can tune the needed restrictions and edit the settings sat originally by the developer. SharePrep cost some money but has really been worth the money (175 USD ), have saved me a lot of work moving files/folders to our SharePoint Online at the office.