The Schneider 90mm does not interest me, so that is out.
Why? it is an excellent lens, with a decent image circle, plenty enough for decent shift/rise.
The 90/4.5 is a design classic, see the recent Schneider /Phase One TS lens for the DF? - its the 90/4.5 design... the great Apo Componon enlarging lens: the same 90/4.5 design. It is also a stop faster than the Rodenstock offerings, and cheaper, and lighter, so.. you must have a good reason to dismiss it. Its an gem imho.
Pluses for the old is that it is cheaper and either fully symmetrical or close to it. I prefer fully symmetrical lenses because I do not like to worry about distortion. Also, the flange focal length of the older versions allows for a less complicated mounting on the Arca R system; no extra bulky box needed on the back.
The newer version I have heard is sharper, however it is retro-focal in design. This means that their is probably distortion (and not a simple barrel or pin cushion, more like a mustache which you need specific software to remove). Also, the flange focal length is long enough to require that extra box for the back side of the RM3Di.
So my questions are, how bad is the distortion on the new lens and is it that much sharper than the older version? Also, how much sharpness fall off is there on the old version?
I owned all 3 of these 90mm at the same time 6 months ago and did tests.
The old 90mm Rodenstock is not that good really. a very tired design. Poor edges.
The new 90mm is excellent, really quite amazing edge to edge - probably my sharpest single lens, especially if you use that large image circle. I use it when stitching.
The Schneider 90mm is closer to new 90mm Roddy than the old, but smaller image circle. I take it when traveling.