Agreed! My M9 lust is pretty high.
As for colors, I have to disagree. On technical terms, the A900 is able to resolve more green hues than any Nikon since the D2x, and the D2x still wasn't quite up to the A900 in this regard. Now, whether you see that or not is, of course, another issue, but I suggest you reconsider your raw converter, profiling, etc. to maximize your A900 files before moving on to another brand, as it seems you may have not been getting the most out of the A900.
My RAW converters were (are): C1Pro, Aperture 2 and 3 as well as LR2 and of course PS CS3 and 4. I have calibrated displays, one being an Eizo 24" latest generation which comes with a calibration device.
I am using a calibrated workflow.
I never liked the colors of the D2X, which was the issue to change finally to A900. So interesting that you put it above the newer Nikon cameras. I have seen numerous samples from D3, D300s, D3X and some D3s on this equipment and I find all of them equal or better to A900.
Either I am doing something wrong or I am color blind - no matter this is my impression and this is what finally counts for me.
PS1: all of these color reproductions can be just forgotten compared to my H3D39. This is also the reason why I am a bit more reluctant about exact color reproduction of my DSLR equipment, as for the real stuff I am using Hasselblad. Maybe I should not think like? Not sure, but this is the way I go.
As I said these decisions are all very subjective and may not be accurate for anyone else of course.
PS2: I actually never found the greens of the A900 so outstanding, I liked more the overall color reproduction, especially in the blues and reds, not the greens, which tended to be too yellowish - in all RAW converters.