I agree it's a nice pattern. What you really need though is a "database in code". A library that handles all the projections, event stream, and especially replays and upgrading event versions automatically.

I'm hopeful that one day it will be a common and useful pattern but it desperately needs language integration to help with the details. That's why right now I can just say stay the hell away. Looking forward to advances in the space to make it viable in production