Well two weeks later and no word from Kimber, but I did get a padded envelope.
No return address, no note inside, but there was a replacement for the the broken part.
It's the same MIM cast stuff, but they've been doing that a while. Even my old safeties that had been working for years were of that.
Maybe the broken one was of a bad batch. No quality control is perfect, but there does seem to be a disturbing pattern and trend with Kimber. I'll run some ammunition though my alternate 1911 with the new safety and see if it breaks.
At least testing to the previous part's longevity won't be hard as it was only around 300 rounds.
Though it will take more than that to have me trust the part in a carry piece.