Well, a most interesting discussion so far.
My take is that Leica may have a tough row to hoe.
For me the comparisons to a P65+ and soon to be launched Hassey H4D/60 do not help with the credibility factor. These are very near FF 645 and 60 meg sensors ... the Phase back is in fine tune with arguably the most sophisticated RAW software on the planet. Those that actually know how to use it have the same opinion about Phocus for Hasselblad files.
Now, I do buy the notion that the S lenses could make some difference. Proof of that is clear every time someone puts a Phase One or Hassey digital back on a tech camera, and uses Rodenstock or Schneider digital APO optics.
I also buy into the idea that the S2 could defy some conventional logic ... the DMR did that, and it seems the M9 is doing something similar.
Again, replacing a MFD system isn't the positioning for the S2 I am interested in. However, that positioning as a replacement for say my Nikon D3X system may not fit everyone's working criteria. In actual shooting situations that I face, the D3X really maxes out at ISO 1,000 ... but I use ISO 400 to 800 most of the time ... but RARELY over ISO 500 for formal shots, commercial images or portraits. The M9 and fast aperture M ASPH optics are for available light work.
I do not have a focal length over 100mm in the Nikon bag. I do have a 70-200G for the Sony and have used it exactly 5 times ... only for my assistant to shoot from a church balcony. When I shot with Canon I didn't even own a Zoom for many years ... 24 to 135 primes, with the least used being the 135.
So, the thought is to make a lifetime purchase here and get out of the Nikon D4X/Canon 1DsMKIV upgrade rat race.
Which raises the specter of long term service and support. Big ? mark. Both Nikon and Canon service has been excellent when I needed it. Not so my history with Leica.
Having been shafted by Kyocera with the Contax 645, Contax N Digital and Contax N, then Leaf with the dead-end Aptus 75s I couldn't use on their AFi Hy6 camera system JUST after getting the 75s ... well, caution is a considerable aspect in mulling this all over.
Marc