I have never had an M9, but I've had an MP. Once you've had one a while, the GAS/lust goes away, and it's just another camera. Then you realise you've got a lot of money tied up in something that can be replaced with something a lot cheaper, and maybe something you prefer. I replaced my MP with an M3 because not only does it cost a lot less, I much prefer it as a camera.
I wonder if many people in a fit of GAS, got the M9, and maybe months or a year later realise they've got $7000 hanging round their neck which could be spent better on a cheaper camera and trip somewhere.