Guy just noticed your comments regarding the 35mm and thought I'd post my experience using it. I have a Schneider 35mm with CF and have found that while I could have larger movements than 10mm I've tended not to exceed that mark. I also found the closer to 15mm the worse it got to the point of being unusable.
I know that I can get 10mm for my 35, 15mm for my 72 and 20 for the 120. Just takes time, testing and practice.
While not having any empirical data with the 180 I tend to agree that the 180 and 35mm might not be suited for what I do. That said until I learn differently the next back upgrade for me will be the 160.
I do like the idea of converting the 35. Maybe we can get a group discount....
Don - I now have quite a bit of experience with the SK 35 XL and an IQ 180.
Without shifts: color cast is evident but very well controlled with an lcc, particularly with the new version of C1. Hand held I apply only a small amount (say 30%) of correction for light fall off - it's part of the very wide look. If you care about fall off you need a center filter and this is going to put you on a tripod. Wide open there is major loss of accutance as you move toward the edge of the frame. The issue with this lens is curvature of field. If you follow Arca's recommendation and shoot at f11 this is not an issue, except perhaps in the last two or three mm in the corners - and that's debatable. Arca, btw, recommends that you shoot essentially all of the lenses on its list at f11.
With the IQ 180 shifting takes you out of this lens's sweet spot with the first couple of mm. Both falling MTF and extreme color shifts come into play.
I'm using the 35 XL primarily on an Alpa TC to make a high end point and shoot so the shifting issue doesn't matter to me. I use my SK 47 when I need to shift or stitch.
I like the way the 35 XL renders a lot. There is almost no geometric distortion. Bokeh is attractive (actually an issue because of the very large sensor) - transition to out of focus is gentle and there are no wild effects. The compact package is very attractive to me.
This lens reminds me of the original Leica 35mm Lux asph. I love both lenses but there is an aspect that drives me nuts (curvature of field in the case of the SK and focus shift in the case of Leica). Leica made a new version - it would be great if SK did the same.
I asked the question about the Rodie 28 and 32 hoping to learn whether they are possible alternatives - the MTFs suggest that accutance falls off a lot as you reach the edge of the IQ 180 image circle, but R doesn't publish MTFs at f11 so its hard to tell. R's data sheets recommend these lenses only with smaller, lower res backs.
BTW, love your images. Thanks for posting them.