The C1/G1 have nerfed Motion Pro High modes at 60hz. But they do preserve a lot more brightness compared to the CX/GX.
The 2020 "X" models had 240hz equivalent with Motion Pro High 60hz (~4.16ms MPRT, removing 75% of sample and hold blur).
Sadly this put them on the dim side of SDR, and HDR is absolutely worthless in this mode.
The 2021 "1" models had 160hz equivalent with Motion Pro High 60hz (~6.25ms MPRT, removing ~62.5% of sample and hold blur).
Sadly, while they have more than enough brightness for SDR, they still come short from reaching the bare minimum of 400nits peak where HDR starts to become noticeable.
At 120hz Motion Pro High, both generations use the x2.666...factor seen on the "1" series at 60hz, so that means 320hz equivalent (3.125ms MPRT, removing only ~62.5% of sample and hold blur but this time from the 120hz baseline).
At 120hz you can use Motion Pro Medium which is a simple x2 factor, meaning that using software BFI, you could theoretically emulate the "X" series Motion Pro High for 60fps games. 120hz Motion Pro High + Software BFI is probably a tough sell.
120hz Motion Pro Medium and Low reaches the 400nits peak threshold on the G1 specifically so that is one valid way to play HDR content with at least some measure of improved motion clarity, provided you have somewhat steady 120fps.
And regarding the plasma question, I assume it comes down to quirks in motion handling that escape strict MPRT considerations.
Ghosting in LCDs, phosphor decay times on CRTs and PDPs, strobe timing problems...
My Kuro looks ridiculously good up to 300pixel/sec, but at very fast motion my GX is clearly better. grey-to-grey limitations and other quirks affect perceived motion clarity regardless of MPRT, though in most cases I'd take a low MPRT w/mediocre GtG over high MPRT w/great GtG...
Just make sure what you see isn't built into the game, some games have pretty bad added motion blur, weird "filmic" effects and even bad anti-aliasing methods that affect motion.