As far as I can see, Von S and Zorita basically re-do the stuff from their Science paper, but trying the different centering techniques. And they discover... that it doesn't make much difference. I could have told them that (here though obviously I never quite finished it...). They say:
Our results, derived in the artificial world of an
extended historical climate simulation, indicate therefore
that the AHS does not have a significant impact but leads
only to very minor deviations.
All is, of course, not sweetness and light. There is more to come, I think.