Can you elaborate on how they're incompatible? I've added Microsoft's implementation to Manu's module, so I fail to see what's incompatible.
Also, the VS2008, VS2015 and all other VS generators are in the same repository, premake-core, which is exactly what I'm suggesting we do here. The end user shouldn't need to get another module to migrate from one action to another. If the end user is running VS2013 and are upgrading to VS2015, having these modules separated is going to cause work for them, if they're merged into a single module, they don't have to do anything as all the APIs are the same. Similarly, if the end user wants to migrate from Windows to OSX/Linux, the module should have support for tools on those systems (there's a new fork of Manu's module that is adding make support). In my opinion, users are more likely to use Manu's module as it will support a wider range of build tools and allows them to jump to another build tool without worrying about their premake files.