Well, so much for that theory. Mine was also no better after updating the firmware, but something changed after several calibrations. In my case, it was after I lowered the target to 130.
Also, in preferences, calibration tab, make sure you have 52 calibration steps selected.
As much as I subscribe to “insanity is doing the same thing over and over expecting a different result,” you might go through several calibrations, particularly ones that keep the black point between 0.4 and 0.5. Start by using “default” for the contrast ratio. After that first calibration with default contrast ratio, use a manual entry to get that black target set point between 0.4-0.5. I’m sure you know this, but just in case: black target is your setting / contrast ratio, so 150cd/m2 / 300 = 0.5 black target.
“Several” meaning 3-6.
Dave