Ok, so I did a little more troubleshooting. Bear with me here...
I cut the config to just the following.
;Heaters
M308 S0 P"temp0" Y"thermistor" T100000 A"Bed"
M308 S1 P"1.temp0" Y"thermistor" T100000 A"Head0"
M308 S2 P"1.temp1" Y"thermistor" T100000 A"Head1"
M308 S3 P"1.temp2" Y"thermistor" T100000 A"Head2"
M308 S4 P"2.temp0" Y"thermistor" T100000 A"Head3"
M308 S5 P"2.temp1" Y"thermistor" T100000 A"Head4"
M308 S6 P"2.temp2" Y"thermistor" T100000 A"Head5"
M308 S7 P"3.temp0" Y"thermistor" T100000 A"Test"
M950 H0 C"0.out1" T0 ;Bed heater
M950 H1 C"1.out0" T1 ;Extruder0
M950 H2 C"1.out1" T2 ;Extruder1
M950 H3 C"1.out2" T3 ;Extruder2
;M950 H4 C"2.out0" T4 ;Extruder3
;M950 H5 C"2.out1" T5 ;Extruder4
;M950 H6 C"2.out2" T6 :Extruder5
creates no error, but when I un-comment out the last few lines....
;Heaters
M308 S0 P"temp0" Y"thermistor" T100000 A"Bed"
M308 S1 P"1.temp0" Y"thermistor" T100000 A"Head0"
M308 S2 P"1.temp1" Y"thermistor" T100000 A"Head1"
M308 S3 P"1.temp2" Y"thermistor" T100000 A"Head2"
M308 S4 P"2.temp0" Y"thermistor" T100000 A"Head3"
M308 S5 P"2.temp1" Y"thermistor" T100000 A"Head4"
M308 S6 P"2.temp2" Y"thermistor" T100000 A"Head5"
M308 S7 P"3.temp0" Y"thermistor" T100000 A"Test"
M950 H0 C"0.out1" T0 ;Bed heater
M950 H1 C"1.out0" T1 ;Extruder0
M950 H2 C"1.out1" T2 ;Extruder1
M950 H3 C"1.out2" T3 ;Extruder2
M950 H4 C"2.out0" T4 ;Extruder3
M950 H5 C"2.out1" T5 ;Extruder4
M950 H6 C"2.out2" T6 ;Extruder5
creates an error.
12/26/2019, 2:14:33 PM Warning: Sensor number 5 has not been defined
12/26/2019, 2:14:33 PM Error: M308: Pin 2.temp1 is not free
12/26/2019, 2:14:33 PM Error: M308: Pin 2.temp2 is not free
12/26/2019, 2:14:33 PM Warning: Sensor number 6 has not been defined
And every time I update the config I shut down the pi and cut all power for 20 seconds right now, just for grins.