I had dreamcolor on Elitebook 8560w, take a look at the flickering on it. It was constant flicker, not like PWM linked to brightness settings, flickering all over the place. I believe so are all, because I don't think the technology permits true 10bit displays. I haven't even met an 8 bit one. If anyone knows any, PWM and dithering free IPS, please let us know, (let's try to make a list or something)
For example, I know AU Optronics B156HAN01 is IPS PWM free, with dithering disabling via this tweak (banding occurs, not true 8 bit)