Hoping for some pointers on how to minimise banding between these apps. Are there any tutorials/settings/guides I can pick up on? My google-fu hasn’t been particularly up to the task 
It’s very obvious for many of the B&W photos and although I can minimise, I havent been able to eliminate.
Versions:
DXO PL 5.2.3 (currently updating to 5.3.1)
SLFX 3 5.0.4 (4.3.4)
My first thought is to use 16-bit TIFF, not 8-bit TIFF or JPEG. And to avoid excessively high ISO photography which reduces color fidelity and dynamic range. But there are also various adjustments involving contrast and noise reduction that, if overdone, will cause smooth tonal gradations to be lost. And then there’s the calibration of your monitor: a lookup table (LUT) on a low-color-resolution display or a poorly calibrated grayscale will also introduce banding in gradients/ramps.
I haven’t experienced any of these problems very much. If you can provide more details about your workflow and system, sample images, etc., maybe some pertinent suggestions can be provided.
Thanks Greg, will dig out some images with egregious examples.
On the road of eliminating cause…
Settings: TIF export is 16bit (double checked!)
ISO settings for the photos are low (200)
The monitor is the 5K monitor on a late 2014 iMac model (new Mac arriving in Sept, cant wait for faster processing). Will recalibrate it.
I dont think there is heavy contrast or NR… but will go over those settings. It might also be some of the Nik app settings. I do prefer low key B&W and may have to look more closely at some of the associated settings.