E2EE because I wish for a software that you don’t need to self-host. We here on the Lemmy Selfhosted community are lucky to have the skill to do it, but I want other less tech-savvy users to also be able to use this service without having to trust a third-party.

It makes backups much more complicated

You have a point, but if the server acts just as a blind relay to facilitate synchronization, you just need to run this app on a couple of your devices and you have a distributed backup you don’t even need to think about. A copy of all the synchronized documents is stored on your device(s), and it should ideally be exportable at any time, so I would say you don’t need to also have a backup on the server. If you happen to lose all of your devices, you can just add a new one and in a few minutes the server will send you a copy of your data. I would say that makes it unnecessary to keep a plain-text backup on the server, what do you think?