I read Puts' review, based on the link provided by the OP (thanks for including it Bob).
It seems Puts started out comparing the X100 to the Leica CM and X1 - fair comparisons IMO (they are all luxo fixed-lens compacts). Here the analogy would not be a Bugatti and a Corvette, but an Audi and a Lexus ("semi-affordable" German vs Japanese luxury items).
I think he wandered into the M9 comparison primarily for rhetorical reasons. If I remember correctly, Puts, like many others, has been speculating about what direction Leica might take with the M series rangefinder. What will/can an M10 be like? Simply a M9 with a more recent sensor? Or are there other ways they might integrate modern technology while still retaining the essential appeal and functionality of the classic M design? The X100 seems to have provoking such musings among other commentators, probably because it combines high build-quality and a retro look along with a dual-system viewfinder. (OT, I don't consider the M8/M9 to be self-consciously retro in the way the X100 is, but that's another discussion I think).
The upcoming Sony NEX7 will likely generate further discussion along the same lines.
Puts comparison between a current APS-C and a two-year old FF sensor is interesting (and not entirely surprising) from a qualitative perspective. But I agree with Bob when he says it's really an apples to oranges comparison.
Extrapolating from Puts' article, another question poses itself: going forward, if Leica digital-Ms are not to be defined strictly by the technical quality of their sensors, their "retro" styling, or their possession of alternate/optical viewfinder (because other new cameras can provide rough equivalents of these things), then what are to be their defining features? At the same time, can a future digital-M incorporate any of the technology found in cameras like the X100 (dual-style viewfinder, live-view, AF, etc.) the upcoming NEX7, the current GXR Mount A12, and still retain it's essential Leica-ness?
The first question is easier to answer than the first, I think. Lens selection and quality, rangefinder focusing and ergonomics still make the M-series unique, as do the optimization of the digital-M sensors (no AA filter, micro lenses, etc.). These are the reasons I recently chose to buy an M8 as opposed to a X100, NEX5n/7, GXR, etc. (My "new" M8 also has something else these other cameras don't have: a roundtrip ticket to NJ to fix the vertical line problem ;p)
But what if you added a true rangefinder to a GXR with the new Mount A12 module? Or a digital/live-view rangefinder to a NEX7? And could a Leica M10 or M11 incorporate any of the features of those cameras and still be a "true" M-series camera?
This is a more intriguing question I think, and more difficult to answer. Leica chose to answer "no" to a similar question in the 1980s & 90s (where the CLE and Hexar RF were technologically "more advanced"). I wonder how they will answer it this time around.