Thanks for having a look at the motion engine too!
Just to stress that one more time... I think that motion interpolation is a good thing to make up for the uneven source fps <> output Hz discrepancy (like 50fps @ 60Hz) which inevitably introduces micro-stuttering. There are engines (like on Sony) that can compensate it pretty well, without introducing a soap opera effect or too many artefacts if you don't crank up that Smoothness slider. I do care about image quality, but I am not a purist. I probably know more about it than most people who start crying around when they hear the term "motion interpolation".
With my origin being HTPC, I had a fair share of issues with refresh rate switching in the past. Moreover it is not seamless and I absolutely hate the inconsistent UI reaction times. UI at 24Hz is downright awful.
Here is how my perfect motion system looks like with a true 120Hz panel:
- 24p is played with a 5:5 without any motion interpolation
- 30/60fps content (either i or p) is played at a 2:2 or 4:4 without any motion interpolation
- ONLY PAL content (25/50fps) is motion interpolated to 30/60fps and each frame is shown for 2 resp. 4 refresh cycles on the 120Hz panel without further interpolation (to not stress soap opera)
Things are again different for 24p content when using an external player via HDMI where you are limited to max. 60Hz output. Still a TV could detect and reverse a 3:2 pulldown and perform a 5:5 on the 120Hz panel.
PAL content is getting less anyway. Most stuff on Netflix and Amazon is 24p and even on YouTube you will find much more 24/30/60fps than PAL content. Phone cameras hardly ever shoot PAL by default, even in Europe. PAL nowadays is only used for legacy TV production.