Every time I manipulate clips both in the timeline and in the speed, size/position, section, camera/zoom effects I notice a much greater fluidity in VPX than in MMS. Is this the same for you? Or do you not notice?
Comparing full version to full version - I get no perceived difference when comparing like for like effects, editing etc.
IMHO where VPX excels and gives a better 'feel' during editing is having both the Source and Program preview monitors, and audio syncing - MMS only syncs to the nearest frame, VPX has a much finer precision.
Even though I'm still using Windows 10, in my environment VPX stands out and you brought the terminology very right: more precision in VPX! (I evaluated this in the speed effect when I was positioning variable frame rates with the mouse) Thanks!