After playing with my Summit for 30 minutes during my lunch with both a new front and rear diff gear I was unable to break anything.
I was running it up & down a large pile of ice hills, through a muddy puddle, and around a wet and plowed astroturf baseball diamond. Full throttle in high gear, low gear, and low gear with diffs locked. No problems.
It was a very nice change and the truck is now living up to its potential. The next step: the local skate park this Saturday without the skateboard punks ruining perfectly good poured concrete ramps.