ProjFS can solve some of the same use cases, but is different by design. It is basically local file storage with a virtual backend that can provide files and data to the local file system. Once files are local, the provider is not asked when files are accessed or modified. The provider can monitor changes and synchronize them with the backend (with chance of conflicts). The provider also needs to manually update the local view when the backing store has changes. It appears to be built for OneDrive. It is way more efficient for many use cases, but also requires more effort to synchronize and resolve conflicts.