We should release a newer version of the SDK at some point. This new version should include new logic for generating an addon's minVersion and maxVersion fields (including whatever we do for bug 884924), since the actual SDK code ships within Firefox now. We can also probably flip the default behavior of cfx xpi so that it strips out the SDK modules from the xpi by default, and you can optionally have cfx NOT strip them (bug 885416).
Bug 863768 is another versioning issue for the SDK that we should probably fix in the next SDK release.
It sounds like this will still ship with some version of the SDK modules (otherwise, how could cfx xpi have an option to include them)? If not, I'd like us to consider bug 857800 (retire cfx docs) as a blocker for this too.