Very impressive, one more congratulation from me. And a couple quick questions:

How do you handle conflicts? E.g. If two users change the same scalar value (of an integer cell, let's say) at the same time. Do you accept one and throw a warning back to the unlucky users?

How much to you cache locally? I had begun a framework such as this at some point, with the ultimate goal of being usable offline via the localStorage cached version (and sync upon connect), so I have a good idea of how much pain you must have gone through sorting this out :)

You wrote your own real-time database engine. You're nuts! (in a very good way). Have you written anything about this? It would be interesting to hear both about the database and the experience of "rolling your own" at such a low level.

You guys need a dev blog.