Since there are apparently engineering issues with getting OneDrive and OneDrive for Business to sync files with each other, Microsoft should offer a free OneDrive for Business tier similar to Dropbox's 25MB options (or allow unlimited "Shared with you" storage on a free tier. This way external contractors and collaborators could at least share and locally sync documents with organizations that use OneDrive for Business. Currently the only option is to use a competitor like Dropbox, or Google Drive which is a shame. The profession and consumer versions should really be compatible with each other but until them give us an option that allows us to sync files with outsiders without requiring external parties to spend $5/mo on a business license!