We are working on the tail end of a migration from on premise resources (Exchange, File server, etc) to completely "cloud" ie O365. Mail, domain, AD, all has gone very smoothly. File server too, ...

The obvious question here is why Metalogix would bother doing that when either solution can effectively push content in or out of SharePoint, or enable users access to content located in SharePoint?

SharePoint 2016 Release To Manufacturing edition is already out and the final version, which will be out May 4. One of the features that some folks are pretty excited about is called Durable Links.