Going Serverless - Personal Backups and File Services

I am help manage a small company that is using a SBS2008 server. We've migrated their Exchange to Office365, so the local server is basically just used for file services, profile storage, and Active Directory. Their overall file usage including profiles is 70GB, so pretty small overall.

Since exchange is no longer local, i've been thinking it will be good to go serverless eventually given the cost and management considerations.  Right now they have a Synology 213+ NAS that I have been planning to use for eventual file services, VPN, website, etc.  
However, since we have the E1 package of Office365 I'm thinking of trying to leverage that for some of these options.

Any suggestions as to the best way to handle file services? Use the synology or try to push them into office 365? We're talking about 10GB for their main 'share' so nothing too crazy.

However, the one thing i'm not sure about is personal files on their desktops/laptops. Right now they use roaming profiles to sync their files with the server, but once I go serverless (synology or 365), i'll need a way to backup their desktop/my documents regularly. Does anyone have any suggestions?

I'd like to start moving over some of these items and then as they get new machines I can just no longer join them to the local server domain (although I will miss out on that AD domain management, but with 6 users I can't imagine it being a big deal to just use local accounts).