Just stumbled over an old article I read here in the UK and reminded me of this thread. It's very interesting, although they don't link to the source info: https://www.yourchickens.co.uk/care-and-advice/the-perfect-perch-1-2842822
Thanks, I had not seen that article or the German study it referenced. It was an interesting read. I could not find that study but I'll admit I did not search really hard. Maybe someone else more diligent would have better results.
The results of a study like this will depend on the assumptions they make when setting up the study and the criteria they judge it by. Why did they choose the size perches they tested? I'd love to see why they chose to not test a large diameter round perch or a wide flat perch, for example. Are their assumptions on the importance of pressure that important? Would other factors perhaps be more important? Not just mites but maybe how much below freezing or how hot it might be? I'm sure there are others.
They make a good case for what they are studying but I consider it more one piece of the puzzle and not the entire picture.