I think it will be tough to find someone who has direct experience with both lenses on the newer digital sensors, so Drew is right in the end: you will probably have to compare them yourself.
With all due respect to Drew, that sounds like a generic response to Rodenstock (Rodi) vs Schneider (SK) lenses, how the
wide-angle end of their designs are different and how those differences are (to some degree) lessened by the new IQ4 150 BSI design. SK wide-angle lens designs have exit pupils that are closer to the sensor vs Rodi's, so they exhibit more severe color casts on FSI sensors. The new BSI design reduces that pretty dramatically. The lenses you quote above are longer, so the above-mentioned color cast is not an issue with either the Rodi or the SK on
any digital sensor available now or in the past.
I am a little confused by your post, since the topic title refers to the IQ4-150, but the text in your post asks about the IQ3 100. Regardless, I think Drew is correct in that the Rodi probably wins in the detail department. That SK Apo-Symmar was designed for 4x5 film. You can see that in the MTF chart here:
Apo-Symmar 5.6/180LNote the image circle is 277mm, the graphed lines/mm are 5/10/20, and the f-stops are 5.6, 11 and 22.
Compare that with the HR's MTF on page 12:
Rodenstock LensesImage circle 80mm, lines/mm are 10/20/40/80, f-stops 5.6 and 8.0.
So, at least according to the MTF's the HR will render better detail. That will show more dramatically pixel peeping with the IQ4 150. However, in general I find Schneider's MTF's to be conservative in the center, but liberal in their claims of image circle vs Rodenstock MTF's.
As for weight, believe it or not they are pretty close. Including the Copal shutter but not the Alpa helical mount, the Rodi is 425 grams vs 435 for the SK, even though the SK includes a bigger Copal 1 shutter. BTW, here is a good summary page for the SK's:
SK Lens ChartDave