Per a suggestion from Andy, I tried rolling forward to the 0928 Firmware that he had temporarily released (recall this "reset" the gain scale so that 0-100 was 0-62 on the 0731 firmware) and the NR is still happening (easily seen on my street/driveway) - again, gain=ZERO and 2D/3D NR is set to zero. Daytime with shutter speed set to 1/100s (and same exposure at 1/200s) so there is plenty of light.
I ALSO tried using the 0827 firmware direct from Dahua ... but this also made no difference. The "gain scale" is easiest to check at night, so I'll do that to see if it is "0-100" or "0-62"
WRT Gamma: I tried this on all three firmware's and it made no difference in the NR. Setting it to a lower value results in a darker image ... and "35-40'" on the T54PRO-ZE was semi-close to what "50" shows on the 5442-S3 ... during the day - TBD at night.
WRT Sharpening: This does make a difference ... but looks like it is sharpening an image that has also been NR'd ... so if something has been "smeared" out (even with NR=0), there's ain't much to sharpen there!
WRT Iris: I did try changing from 100 to 50 ... but that made no difference on the NR issue. FYI that I did confirm it's "working" as (in manual mode), I set the shutter to 0.01msec (1/10000s shutter) and at IRIS=50, I got a dimmed image ... and then brightened up when I set IRIS=100.