So, I completed the power train replacement. After the standard breaking-in period, it's been great and really fun to shift gears and get up to 37mph or so on the flat.
However, earlier this week, I had a problem! When I was riding home on Friday, my chain randomly shifted to 6th gear - I'm assuming that this was caused by a mis-adjusted derailleur. (they seem to de-adjust over time)
It derailed the rear chain and pulled off the smallest chain that's on the motor. I replaced the chains and slowly rode home, thinking nothing of it. Then on Monday, I headed out in the morning and my middle chain derailed! No big deal, I fixed it.
Then, Tuesday, everything goes to shit. I'm good for about 15 seconds, then the chain makes a very loud noise and binds up. Here are the results.

You can see that one of the 10-32 bolts is sheared off completely

Destroyed chain

Deep gouges in frame

another angle
I just went to the bike store and got a new chain and sprocket. I'm guessing that the old chain or sprocket got bent when it randomly shifted under load, and caused a catastrophic failure after a couple miles.
Here's a picture of the bike as it is this very moment (I'll get around to replacing the sprocket and chain tomorrow)

Here's the new sports-action cam that I got for my birthday today! I'll finally be able to post some quality videos of me riding around, all DC-in-GC style

Here's a short video I took with it in my garage. It's pretty dark in there, but it is HD!