Larger metal hub is acting as heat sink IMO and the polymer dust...

Larger metal hub is acting as heat sink IMO and the polymer dust shroud / enclosure would conduct very little heat in or out as air between it and disc is such a bad conductor hence my concern about heavy use. That said - standard brakes are pretty light weight built to budget to be adequate as you have experienced and pretty average materials so them quoting better performance wouldn't be hard to achieve IMO. With modern cad design it is easy to create moulds with fins etc to be cast if it was to help. With sibs I think they have machined fins in to help dissipation on the hub.



Oil in the sibs is a good conductor and on larger trucks as you say it could go through a cooler.

Had the axles out of a fergie 165 doing bearings last year and have a mates larger massey with a siezed clutch to split when I get the motivation. Why does it always happen at the boggy end of the paddock with slasher on rested up against a tree? If I can jack it up I'll select reverse , start it , drop it of the blocks and see if I can get it to solid ground up at the shed.