As with many other TT01 upgrades, this one is essential before changing the motor or gearing in your chassis.
A more powerful motor, or a motor geared lower, will generate more heat. The use of a metal motor mount helps work as a heatsink to cool the motor down. Also, when using the standard plastic motor mount, the heat can cause it to warp.
The only bad thing about this motor mount is that it does add extra weight to the chassis.