Stan,
Hartmann’s museum always had an LGB mogul and and an Americanized LGB 0-4-0. Parts would wear out occasionally, but they had big hours and ran for years and years.
Other considerations…
What are the radii like? The 0-4-0 will obviously last longer on sharper turns.
What is the controller like? Will the trains run constantly, or will they be on timers or push buttons.
If timer or push button, be sure to use momentum to save the gears. If running constantly, be sure to use low-resistance LGB or Piko ball bearing wheelsets on all the cars to reduce drag to keep the motor from getting too hot.