The ember ship engine is modular in architecture. These modules can scale independently under load. Never worry about outgrowing your backend.
Data privacy built-in
Personal information can be stored separately from the engine itself. You can choose to have all privacy sensitive information on your own servers, with only the actual functionality in the public cloud.
Use any front-end
Using the engine is through industry standard restful APIs. This means you can build any front-end you like; an app, a desktop application or a web site.