In reply to AlanLittle:
I remembered that I have a fancy pair of Sidas insoles in my snowboard boots, to I tied an experiment. One sidas insole, one standard issue scarpa, ten hour via ferrata outing.
In the morning I definitely thought I could feel a difference - sidas softer and with less heel lift. And in the evening my left foot was a lot less tired than my right, which had also ha cramps on the route. Only: the left was the one with the stock scarpa insole.
So that's a bit of money saved then.