I've previously written about how I can't currently recommend EtherPad on Sandstorm.
I'm currently prototyping a task tracker in Sandstorm, and overall, as a developer, I do love what I see! It cleverly separates the problem of account and document management from the problems of web application creation and storage. Documentation is very clear and only a few challenges so far in understanding the abstractions.
As a framework / platform, I currently can recommend Sandstorm if you want to create a Google Drive-style web document service that you can maintain and manage yourself. And the great thing about it all being open source is that (were there infinite time in this world) I could at least pry EtherPad open and sort out what's going on with its performance; good luck doing that with basically any online document service.
https://sandstorm.io/. Good stuff.
#sandstorm