I have the same (ish) usb a4 lightpad, and I think it works well. No noticable 'noise' from it.
I did read up on using flats with my asi 1600mm-c and found some things that was true for these dedicated CMOS cameras.
Most of my calibrating was baseed on how you would do with a dedicated CCD, so somethings were needed to change.
First problem I had was Using Dark, Biases and Flats. For the noise of the CMOS chips it is more valuable to do Dark, DarkFlats, and Flats.
This is partly becaus the biases has to short exposuree lenght and causes some random / varying noise.
Because of this it is recomended to do flats with a exposure length of 0.2 seconds or longer, to avoid the varying bias noise, and instead of biases use DarkFlats to calibrate the flats.
So my process no is Lights, Darks, Flats, DarkFlats all at same gain, offset, focus and teemperature
Darks: same exposure length as Lights (but covered)
Flats: 0.2 second exposure length or longer. (I use 0.2s with the dimmable a4 led pad at lowest setting). You use the same focus as when the scope images the sky, so any light source at the devshield should be seriously out of focus, and a even field.
Dark Flats: same as flats, only covered.
In Siri (from googeling, I use PixInsight), you can stack the Flats as Lights and the Dark Flats as Darks. This gives you a MasterFlat
Then stack the Lights with all the darks and the master flat. (This would be the same as calibrating all the Lights with a [Dark Flat calibrated] master Flat and a master Dark in PixInsight), before registering and stacking the Lights.