The bafang bbshd are a mid drive motor where Rad uses a hub motor so they are two very different systems that can’t be compared. But yes hill climbing will over heat a motor and shorten its live.
What you have read about melting gears is related to mid drive motors, power and user abuse. This is happening to bikes with 48v 25a controllers on a 1000 w motor well above the class 2 bikes Rad sells. The rider is applying to much torque at low or no speed ( wheelies and burn outs) and because of the power of these motors the plastic gears are being stripped out then spinning at high speed to make it look like it melted.
The torque on a hub motor isn’t any where near that of a mid drive so you would have to be asking a lot of a hub motor to over heat the motor or strip the gears.