Until the SL appeared I was pretty ignorant of the more modern R lenses. Your 15 looks flat out incredible. I also see the last 50/1.4 is meant to be really something, and costs considerably more than a 50 Lux ASPH today on the used market.Mine was made in 2002, and still new in the box. Despite my general belief that R lens prices can be bargained down about 30%, this guy knew what he had, and there wasn't time for psychological warfare.
The SL is a great platform for working with UWAs, like this one, the M's 18 SEM, and the R-19 (which I believe Godfrey is using). These lenses really reorganize space for you. Thinking back to work Friedlander has done with his SWC, I realize that he gets so far into the middle of things that different planes in space end up interacting through transparency. One of my pictures with the 15 in a conference center in Montreal has that flavor. Anyway, there are lots of things to try.
scott
I use the M9 and my widest is the ZM18 at the moment, which is really a super lens, but I do lust for one a bit wider. The CV 15s v1 and v2 have really dropped in price with the introduction of the new v3, but both seem to need considerable correction for colorshift.