Here are some measurements performed on tonearm materials (including panzerholz). I would expect material frequency respons to directly impact total system frequency response in this application.
https://www.reed.lt/5174/research/wood-vs-the-rest-testing-armtube-material/
I loved the Reed wood tonearm resonance data when I first saw it some time ago. I still do as I think there is a Reed tonearm in my future for a variety of reasons. This is very nice data I can wrap my arms around! But examination of the data leads to more questions than it answers, at least for me.
1) To begin, the control response of the system is missing. What is the response of the system without any tonearm? That's an important control and without it, what the tonearm is doing or contributing to the result cannot be meaningfully interpreted.
2) What does the "acoustic properties under perfect conditions" mean exactly? Why is a 40dB rise from 0.5 to 0 Hz "perfect"?
3) Let's assume that the "perfect" response is as they say; namely perfect (translation= most desirable?) Well, then what do we make of an arm such as cocobolo that is up 20dB from "perfect" at 0.5Hz and down 20dB from "perfect" at 0.2 Hz? Is this good or bad?
4) Pick any response for any of the illustrated woods? What is the sonic effect of the responses shown? In my system, or any system, is the idea to re-create the "perfect" response with your chosen tonearm wood? I have no earthly idea. Do I want a response typified by Wenge or Red Cedar, or other? Pernambuco anyone?
5) Seems to me the only way to tell is to try one and see if you like what you hear. This is the classic "ice-cream theory" of choosing audio gear. (i.e. there's vanilla, chocolate and strawberry. You pays yer money and you takes yer choice). I don't see any shortcut around that approach for picking your Reed tonearm wood.
So the data is the data. I don't have any reason to doubt the methodology, but I have no idea what it really represents, Nor do I know what to make of the data presented for the various woods in terms of what might be best in my system. No doubt the woods may all sound slightly different. But the fact that we are indeed dealing with a system just adds to the complexity of the issue. Wood "A" might sound best with cartridge "X" , but wood "B" might sound better with cartridge "Y", etc. What guidance other than listening is there to figure that out?
The variation for most of these woods is in the range of 0 to 1 Hz. Does that truly matter in most systems, for which we can assume has a lower limit of reproduction significantly above 1 Hz? Wish I knew. If someone told me they chose cocobolo because they liked the color and it sounded good in their system, it would be hard for me to find fault with that rationale despite any of the data generated by Reed for the various tonearm woods.
I wish it were easier than that to know the correct choice for tonearm wood for a Reed. If anyone has other insights that might be helpful, I hope you'll share them.