I own both the 5DII and the M9. I don't own the Nocti, but I have used it plenty of times.
One thing I can tell you is that at low ISO (400 and under), the CCD of the M9 destroys the 5DII (and even my 1DX) - You heard it.
Yes, everyone likes to dog on Leica shooters, but it's a great tool that when coupled with Leica glass is an absolute beast.
FYI the Nocti actually costs closer to 11K new
The difficulty with taking these claims seriously is that there are little to no comparison photos. Leica images are often described using airy fairy pixie dust descriptions.
I'm not a Leica user so what I'm about to say is a result of my generalistic interpretation of Leica vs Canon from an engineer's point of view.
Mechanically, Leica's are probably works of precision engineering. I believe that optically they can be very good but in any event I highly doubt that 'Leica' electronics can compete with Canon's.
The M9 sensor is manufactured by Kodak and not too impressive if you look here:
Leica is a niche product, and they have a lot of elitist followers to the brand name. In that sense the true technical ability is secondary to the product image. Such is the world of marketing.
Listen, I have no agenda with the Leica. I love my canon gear.
As I said, the M-9 is pretty terrible at higher ISO, but at lower ISO with no AA filter coupled with Leica glass, it does give superior (and yes, unique) images compared to my 5D2 and 1DX.
And seriously, stop reading DXO mark. Waste of time.