My father still has a Hough 65 (1971) that we have in a field right now. Eventually I want to restore that machine.
The air over hydraulic brakes are terrible. The air side is problematic by nature and the hydraulic side is weak (master and wheel cylinders seemed to blow out). We always had problems and rarely had working brakes. It was used as a snow machine and yard loader.
They are slow but powerful. Through a lot of customization, we changed the 4D batteries to the big CAT batteries and made new battery boxes. Extended the hood and put a 466 in place of the original engine (365?). Original drive train and hydraulic pumps and the hour meter was broken well past 20,000 hours.
We also have a baby straight frame H30. That has regular hydraulic brakes and are a total nightmare as well.