Just started running it so it is a bit soon to rate durability. Also, it has good low speed performance but as a brand new unit I understand they take a break-in period before reaching their maximum high speed performance levels.At present it is clearly slower at the top end than well used examples of other similar Bachmann engines I own.
This engine has become my favorite. It runs well and is responsive to the controls. It moves with a great deal of speed. It is the n scale engine "that could.'
I was looking for an 8 wheel medium duty for my N Scale railroad. The Bachmann GP-40 fit the bill perfectly. It looks great and has great detail and best of all runs great.