We've had a rationale up for a while [1] and our first post on incidental complexity also went over a lot of that [2]. But given the above it's certainly not as explicit as you're wanting, because until very recently we hadn't figured out the exact what or how. The plan for the fall release is to present a real system for people to use as well as a ton of content to lay all of that out in detail. We'll be drawing lines between all the various things we've done and all the papers we've read to the real working system - tradeoffs and all. We're actually really excited about it - it's been tough figuring out how all this is meant to fit together and we have the opportunity to present things in a very exploratory way, where people can dig as deep as they want (there'll be weeks worth of stuff). Once we pull a first draft of that together, I'd love to send it to you to get your thoughts.
[1]: https://github.com/witheve/eve-experiments/blob/master/desig...
[2]: http://incidentalcomplexity.com/2014/10/16/retrospective/