It's been about 3 weeks since the launch of M9. I love launch events where people get cameras in their hands the same day. We have DNGs available, lots of first-hand accounts…
Observation #0: M9 is awesome. Except where specifically noted below, I think one can assume the camera is great. If you don’t push the envelope on it then it’s just plain great.
Observation #1: KAF-18500’s noise is similar to KAF-10500’s and, adjusting for print or display density, it is comparable to contemporary APS-C cameras. The best supporting evidence is found on Sean Reid’s site.
At first I thought I was seeing terrible results compared to the D700 but I changed my mind after comparing the grain of hand-processed DNGs and NEFs on my own PC. The noise that’s there also looks like it can be tamed with noise processing plug-ins for LR/PS like DFine 2.0. Hence you still need to stay close to windows during daylight, get faster lenses if possible and brace yourself (literally).
My only remaining issue with M9’s sensitivity (indirectly) is that the M9 lacks a convenient way to fix bad lighting conditions with controlled light because both its flash units are unacceptably awkward. I'm convinced that the M9 with a small flash (see: SB-400) can deliver as good quality as I can extract from the D700.
Observation #2: KAF-18500’s detail levels compare favorably to 24MP cameras but in exchange the risk of moiré is real. The best supporting evidence is found on Erwin Puts’ site.
It would probably have been more convenient to use a 24MP sensor with an AA filter. At this point Adobe Photoshop probably can’t be avoided anymore – and I have been avoiding it – so either learn to deal with moiré by hand and apply yourself on batches, or write a Photoshop macro for that, or get CaptureOne’s moiré removal plug-in.
There exist AA filters that screw into lens like ordinary filters, but so far they haven’t been made in sizes less than Series-8. Still, this is a very interesting avenue to explore. Maybe the company that makes them can be compelled to make smaller sizes to cater to the small rangefinder market.
Observation #3: M9’s system board writes its large files to SD flash memory at a slowish rate. It takes 11 seconds to write a 37MB file, at a rate of around 3.4MB/s, and faster cards aren’t really supported by the system’s hardware or firmware.
Compared to, say a D90, the M9 writes 3x larger files at about 0.5x the byte transfer rate – so if you think continuous shooting on the D90 is compromised, you haven’t experienced an M9 yet. Apparently under some conditions you can get your M9 system board to freeze if you keep hitting it with more frames while it’s busy writing, like the M8, but these reports aren’t widespread. There isn’t a solution for this unless a firmware update adds lossless compression or delivers the faster rates expected on faster cards.
This is fodder for a DSP-vs-ASIC (e.g. Maestro, Expeed, Digic, Bionz) debate that will lead us eventually to the M10. In the mean time the mantra seems to be “one shot is all you need, but 2 or 3 is supported for your convenience”. :^)
Conclusion from the above: The ugly sides of the M9 are now known. I don't see a deal-breaker, but the effervescent enthusiasm phase has passed.