So, who's had the master cylinder reservoir crack while

[John Larson]

John said, oddly:  "So, all in all, it sucked that it happened, but it could
easily have
happened in an emergency situation and I'd have been screwed."

It's difficult for me to picture a brake master cylinder failing under
pressure in an emergency situation, as the ONLY time it is under pressure is
when you induce that pressure during an attempt to bleed the system.
Sitting in your garage, shop, or driveway is unlikely to become an emergency
situation, IME ............................  John