Huh, this doesn't make sense [ unless I don't understand you ]. Calling something a 'crop' does only make sense when a camera was designed for a larger (film) format but is now used for a smaller digital sensor.
Medium Format SLR in the film time never had the ultra wide lenses as the 35mm SLRs. That didn't make them cropped 35mm.
What I was trying to point out is that if you put the same focal length lens on an S2 (which, I'm sorry, does have a 1.3 crop MF sensor, whichever way anyone tries to spin it) as a "FF" MFDB, then the S2 will crop the field of view that you get from the FF back.
This means that - if wide angle is important to you - the Leica is limited compared to FF MFDB, because the focal length of the widest lens available for the Leica and a MFDB on a tech cam are pretty much the same (and that's ignoring the possibility of using a 17mm lens on an MFDB).
In the 35mm world, there are of course lenses with shorter focal lengths available - 14mm if you care about quality, 11 or 12mm if you're not that fussed. That's why it makes no sense to try to think of the Leica as some sort of "super sized 35mm". It's not. Because the systems simply aren't equivalent.
None of this is in any way meant as a criticism of the Leica camera, nor the wider system. It's simply a fact that for those people who are looking for very wide angles, it simply isn't a viable solution. There will of course be plenty of people for whom this simply isn't a concern.
Back to the point that was originally claimed, and that I questioned:
"Until someone comes out with a 3"x5" sensor and thereby creates a new threshold for "large sensor format" I don't see the point fussing over all these similar sized sensors.."
Well, fair enough. Maybe Paul doesn't. Maybe for what he shoots, the above described limitation simply isn't an issue. But many people would see the point fussing over the fact that the widest lens available for the two systems being compared was the same focal length, and yet one system had a sensor size 1.3x the size of the other.
For some, that kind of stuff is important.