OK, I got the scoop. Schneider makes a 100mm APO Digitar, and that's still available, along with a 90mm. These are not the newer Aspheric designs like the latest 120mm.
All of last year it was rumored that Schneider was working a new "Aspheric" version of the 100mm, and it would have a larger image circle in the 110 to 120mm range. That lens has not been produced.
Schneider still makes the older APO-Digitar 90mm (90mm IC) and 100mm (100mm IC I believe) and those can be ordered from Alpa, Arca and Cambo.
There is an big optical difference in the 120mm APO Aspheric (better) and it will focus much closer than the older 120mm APO Digitar. In fact Schneider made both a macro and normal range version of the APO Digitar.
Back to the 90mm HRSW, it's all new glass, takes over a year to cool, so they are much more difficult to find. Supposedly by far the sharpest 90 Rodenstock has made. So it should be a great lens for you, just watch for the possible ghosting.
Older versions of the 90 Rodenstock,
90mm HR Pink band
90mm HR sinor digitar (supposedly built just a bit better) Pink band
90mm HR-W, Blue band, optically different and I believe it needs the back extension.
90mm HRSW, totally optically new and for sure needs the back extension, Yellow band.
Paul