I have the Version 1 piano wire reinforced upper and lower arms still on mine. It's been traction rolled off the track into a wall on our sweeper a few times, not that I'm proud of it, and the arms haven't broken(there is a weird jump in the track if the wrong line is taken).
With the Troy's new front uppers, I'm guessing that will really increase durability.
Regarding that same spot on the track, my F103 on foam does the same thing at the exact same spot. It looks like a little hop, then it comes down, overloads the outside tires and instead of pushing or diffing out... Wham! We can find the bad spot. So I take a wider line and blip the throttle as I pass through. Seems to work.