It just occurred to me, you could use a Phex installer which alternates between installing one stub or another depending on OSX version of user's system. That would save from needing two separate installers. The older stub works in OSX 10.8 (for now at least) so I guess the Mavericks stub would only be needed for OSX 10.9 or later (for now at least.) Not sure any system updates on 10.8 or even 10.7 might affect the useability of the older stub.

However the Phex snapshots archive would probably need two separate versions if they are simply zipped folders.