So tonights adventure included understanding that the 16MHz units work properly when set in the boards.txt as 16MHz, and get firmware set to standard baud rate of 115200.
Not sure how I was overwriting the EEPROM last night but that all seems to be settled now.
Curiously, the 10MHz boards; they only output properly in the serial output when mismatched. Either in the boards.txt at 16MHz and baud at 184320 (115200 * 16 / 10) or the inverse with the boards.txt set to 10MHz and the baud at the standard 115200.
Any idea on why that is?
I've got 3 boards now that have serial numbers programmed- just need to figure out why the BLE module wont take a newer softdevice/firmware combo. I did manage to figure out how to get the BLE module into DFU mode and update the firmware that way but it hangs all the same except on those middle boards which function flawlessly (found out one of them is also a 10MHz!)
So. Close.