Roger et al:
The weird voltage dropping trend as Vcc was raised well past the shunting knee point was my fault.
Yesterday, while tinkering I accidentally connected the resistor that is connected to the upper fet's gate and? to the dropper resistor had its upper lead connected to Vcc.
See the dotted line on the attached jpg.
I must have accidentally connected the upper 66M resistor to the wrong point while tinkering and didn't notice.
Sorry for the confusion. Circuit is operating as expected after reconnecting the resistor to the lower side of the 1M dropper resistor and seems to follow what Micro-Cap simulates.
P
