After wearing the watch for about a week, I plugged it in to upload some new firmware and immediately started having issues with the built-in USB connection on the chip. My suspicion is that the ESD fairy struck again, this time damaging the MCU rather than a power system.  Rev. 5 (and rev. 5.1, which is identical except for adding pads for a current shunt resistor so I can more accurately measure power consumption) includes ESD protection in the form of a TVS diode, so I think I'll take a break for a week or so until the new boards and parts come in rather than continue to destroy components every few days.

The good news: in wearing the watch for a week, I've found that it draws about 8% of the battery per day. This is an extremely rough estimate, but (assuming I can trust the readings from the MAX17252, which I'm not sure of) is a promising sign: that points to an average ~200 uA consumption, pre-battery-optimization but also pre-BLE-enable. I did manage to get ahold of an oscilloscope, so when rev. 5 comes in I'll be able to get much more accurate consumption numbers.