Andalucia: I have exactly the sort of equipment you may be contemplating: an Arca Swiss M-Line 2 with a Phase One 40+ back and the following lenses: Rod. 32 HR, Rod 40 HR, Schn 47, Rod 55 (non-HR), Rod 70 HR, Schn 100 (5.6). My subject is urban architecture, sttreetscapes, etc., usually exterior. I shoot almost everything with two or three vertical (portrait) images in a horizontal stitch yielding large files, sometimes the opposite orientation for vertical images. The minimum requirement for stitching architectural images is a 90mm image circle. The 32mm HR stitched yields a very wide-field image but on the occasions it is most useful for--close in to a building with 15 to 20mm of rise plus horizontal movements for stitching--the 90mm image circle is sometimes not sufficient and the camera has to be tilted up to avoid the image circle impinging on the desired image. Less often but occasionally with the 40 HR as well. Both the 32mm HR and 40HR (less so) require correction distortion after stitching with the Alpa program, mentioned by others, which does a good job.
Stitching makes everything complicated: The LCC (lens cast and fall-off) corrections have to be shot individually and are applied individually before stitching. The applied LCC images, even when shot at the time of picture-taking (which is a must) do not yield perfectly colour matched images, so images after LCC correction need colour matching (which is tedious and difficult sometimes). Then the stitched image needs a custom Alpa lens correction file (modified from existing provided files with any text program) based on its ultimate dimensions. And then, if the image has been tilted up (not the usual case) perspective correction must be applied (and it cannot be applied earlier in the workflow because of the need to use the Alpa correction on images after stitching). A lot of work for stitched images, but it's the only way to get really wide shots which are often needed in urban and architectural photography. (I thought of getting the Phase IQ180 but have been scared off by the reports of even more difficult issues with wide angle colour casts.)
As for quality of lenses, the 40HR is the best of the bunch. The 32 HR can be nearly as good but quality suffers more than the 40HR as you approach the boundary of the image circle. The Schneider 47mm is excellent at centre not so good as you approach about two-thirds of the way to edge of image circle. The Rod 55, while not an HR, can be excellent at centre, but falls off somewhat in resolution as you move towards image circle boundary. The 70 HR and Schn 100 are generally excellent with the 70mm falling off as you approach image circle. The need for a 90mm image circle at minimum elminates many lenses. The 40HR especially holds its quality almost right up to the image circle boundary.
Hope this was helpful.
