Syncthing (syncthing.net) might meet your needs. Runs on Windows, but also on Linux & Mac. Open-source, encrypted file transfers, real-time syncing, optional file versioning. You should be able to install it on a cloud server and have it just sync to whatever you want on your local machine. No static ip requirement - it figures out routing by itself. ...
For backing up data from servers, I'm using AzCopy v10 to synchronize local files to Azure Blob Storage.
Local copy can be considered always authoritative.
Only new/changed files are
Locally deleted files can be deleted from remote.
Azure Blob Storage has settings to automatically retain deleted blobs for some time period.
Azure offers additional ...
Archive Team is currently performing a large-scale archive effort on Google+ profiles. You could make a request for the profile to be backed up on their official IRC channel: irc.efnet.org #googleminus
(They also have an archiving stats overview: http://tracker.archiveteam.org/googleplus/)
Give Lomorage a try, https://lomorage.com/features/, the background upload is still in development. Removing from backup using iPhone app will go into trash box, deleting directly on Raspberry Pi or Windows/Mac will cause inconsistency between db and file system, even it has consistency check to find the inconsistency. The metadata (geo, orientation etc ...