Squawk 8888
The T/R versus carbon brakes scenario is that of using Autobrake for landing. If you use Autobrake, the unit senses total retardation, so if T/R is used the brakes will be modulated to achieve the selected retardation. Carbon brakes do not react well to modulation - they are much better at having one constant application being held. This gets them up to temperature quickly and reduces the wear. Soooooo.. Reverse idle and medium Autobrake works well and costs less.