Thank you all for the info. If I go with wood I would like to us a North American species. I can see the softwoods like spruce cracking / breaking / wearing or even your softer hardwood species where as your tougher hardwoods like your eastern iron woods, white oaks and hard maples being stronger.
This info has sent me down the wood rabbit hole and so far have found the following info:
A lot burnishers use the non native to North America rosewood Cocobolo which has Janka rating of 2,960 Ibf
Native to North America:
i) Southern Live Oak (Quercus virginiana) has Janka rating of 2680 Ibf
ii) Eastern Ironwood (Ostrya virginiana) has Janka rating of 1,860 Ibf
iii) Hard maple has Janka rating of 1,500 Ibf
iv) White Oak has Janka rating of 1,360 Ibf
As a reference your typical White Spruce has Janka rating of 460 Ibf.
This raises the question if a good burnisher is based on hardness why not just go with metal or are there other factors?
I couldn't find him so if you have a link I would appreciate it.
kgg