Currently it's going to blow up big time. You're not going to be able to upgrade an existing site without some significant code changes. We're still figuring out whether these are something we can alleviate in the future . Our code quality improvements and some reworking of MVC have lead to better code under the hood, but some required changes to the way controllers are named.

Stay tuned. We may try and walk some of these naming requirements back if they prove too onerous for too little benefit.