This is an exciting plugin but in terms of execution, I'd have preferred it based on 3 separate instances rather than MU.

With MU it is difficult to keep different versions of plugins, something which you might want to do during development, staging and production. But ultimately you might want to have the development version on a local machine and the staging on a different server.

(I'm also not a fan of MU unless you are truly building a 'network' of blogs, but that's just a personal preference)

Seeing as author mmaunder is reading these comments, I'm curious to hear whether he'd be interested in having this plugin developed to support multiple discrete instances, perhaps with community development? I might fork and do a pull request if he is.

this looks very promising, how does this differ from the one click staging plugin by WPEngine?