I am jealous. Gerold's work is incredible. (I keep thinking about the string he developed for Rabbath.)
the rabbath string is likely similar to tempera - it's a synthetic core, so they share that.
I received my sonores basso/gut set and installed them yesterday.
I have a minor injury to my right elbow and can't play very much for a few more days, but my initial impressions are that this is nothing like any other string i've used. in many different ways.
once i've played on them for a few days and they're good and stretched out i'll post more thoughts and maybe record them. would be smart to re-record something i've played on tempera to demonstrate how different they really are.