Anything CAN be broke, just depends how it is used, some of you know what power dividers are (they connect number 2 and 3 axle on a civi 3 axle truck) it has really thick gears, you would think they would be impossible to tear up, yet I have repaired quite a few, and EVERY time it was lead foot driver, another example, I can take a cat D9, put it in HARD rock, get 2,000/3,000 hr a year with just normal build up and maintenance, on the other hand I could take that same CAT, and slam-bang in the hard rock an be lucky to get 40 hours out of it before it is DOWN for the count.
So if you drive these with some common since (becoming a rather short supply), NOT peddle to the metal, not on the edge, not to the wall, not 110% of design, ect., it WILL last like any other piece of machinery and be fairly cheap to operate, if you don't you will need very deep pockets..