Surely a small housing for the Leica M9 adapted to take the Nikonos 15mm lens (or the RS lenses) would make more sense?
We did consider the Leica M9 (as well as the M8, and the Panasonic G1, GH1 and GF1), but eventually settled on the EP1.
My main concerns around an underwater M9 are:
1. It would be difficult to frame images underwater. The M9 doesn't have liveview, and the shade of a 15mm lens blocks the M9 viewfinder, so you're stuck with using an external viewfinder.
2. It would be difficult to focus underwater, for the same reasons as above. This would turn a rangefinder camera into a scale focus camera.
3. The M9 doesn't have an anti-aliasing filter, which some people believe could cause problems with underwater images.
4. An underwater M9 setup (including the housing, camera, lenses, strobes) would be too expensive for many people.
5. There's a small issue where I think the lens mount would need to be unscrewed from the M9 to accomodate the back of the 15mm lens (even the new version 15mm). I'm not sure how many people are comfortable taking parts off their US$7,000 cameras.
In the end, although there are no unsurmountable problems with taking the M9 underwater, it seems like the EP1 will be much easier to use (especially framing and focusing with liveview), priced so that many more people could use it (around US$6,000 less than the M9), and provide only slightly lower performance than the M9.
David Lewinnek
www.piratepro.com
david@priatepro.com