Ideally, I'd prefer to have the Elmar 24/3.8 to use with the M9.
No plans for an M9 in the near future, however. And even if I do come across one, the cost (even used) would probably be prohibitive enough to dissuade me from taking it backpacking, where it would potentially be exposed to harsh treatment. So for the foreseeable future, the M8 is my backpacking landscape camera. (and for that very reason, the ZM 18/4 is sorely tempting!)