In case they are of interest to anyone, we have published some academic / professional papers around Coderetreats. Sorry that some of these are behind paywalls.
Parsons, D., Susnjak, T. & Mathrani, A. (2016). Design from Detail: Analyzing Data from a Global Day of Coderetreat. Information and Software Technology, 75, 39–55.
Parsons, D. (2015). Refactoring coderetreats: In search of simple design. InfoQ. http://www.infoq.com/articles/refactoring-coderetreats
Parsons, D, Susjak, T. & Mathrani, A. (2015). The Software Developer Cycle: Career demographics and the market cl... Paper Presented at the 24th Australasian Software Engineering Conference (ASWEC 2015), Adelaide.
Parsons, D., Mathrani, A., Susnjak, T. & Leist, A. (2014). Coderetreats: Reflective Practice and the Game of Life. IEEE Software, special issue on reflective practice, 31(4), 58-64.