I suggest a cloud service that mirrors contents on your devices. (Dropbox would be an example).
If I may, I'll share with you some corporate/government information management terms that might help you manage your own documents.
Understand the difference between "transitory records, corporate memory, and reference material."
Transitory is stuff like 99% of your email that will be irrelevant in short order. Example: you email a follow-up document to the tax-man. Keep that only until you receive notification they have accepted your tax return. This is the "cover your ass" stuff that says you did something but becomes stale dated with time. Receipts for warranty purposes are another good example.
Corporate memory is stuff you should keep: tax returns, let's say. Even those become stale dated after a while. (what's the rule? 7 years of tax returns?) After the "retention period" elapses, you can dispose of them, unless there's some other reason you'd keep them longer.
Reference material: you are under no obligation to keep this stuff but everyone has a shelf full of it. Examples include encyclopedias, user manuals and the guide the tax man publishes on how to fill out your tax return. Key here: you were not the author, therefore, despite you keeping this for your own convenient reference, you are under no legal obligation to do so.
In my experience, you can usually get away with electronic copies of all of the above. I've had major chain stores accept digital receipts for returns and exchanges. (IKEA, for example) Things that require original signatures (diplomas, for example) can be scanned for ease of transmittal but you still need the original in a fireproof safe somewhere.
