I have SS on the 1100ez and oem rubber on my two 18 y.o. FZ1s. I can lift the rear wheel with a passenger with either set up.
My personal "feel" preference is rubber for panic stops. More forgiving before lock up. I probably had two or three incidents this season where SS may have been too much. Easy to say don't grab too hard in panic, little harder to not do.
If I were replacing I'd go SS just because they are cheaper.
Everyone else's results are probably different.
I could feel a CONSIDERABLE difference when I rebuilt my master cylinder and calipers...I was fortunate to be in SoCal and went to a local shop in the Inland Empire and had them replicate the old line.
The brakes on these old GS' aren't like the newer bikes (2000's) where grabbing a handful of brake spells trouble.
I would go with braided lines on vintage bikes...I did a cut out of the rubber and see how aging affects the rubber.
Just my two cents.
Ed