I was wondering if you would consider adding SpiderOak as a cloud sync possibility? I use it, and it’s pretty great.
I believe this setup wouldn’t need E2E, as SpiderOak segments/encrypts everything as a rule. Also, you have control of your private keys, whereas with other cloud services they have both your private and public keys… which basically makes them you… spurring the need for encryption on clouds in the first place. There are still MITM attacks, but if somebody is watching you that hard, you’re probably already screwed. lol