I tried, and thank you very much, it is waaaaaaaaaayyyyyyyyyyyyyyy better than before.
I don't know why the f*ck if I play with Render Quality parameter on PimaxPlay, once in DCS it starts to stutter again ... But if I uninstall everything except DCS, and reinstall in the order you presented above, it works, it rocks better than before.
I'll try to find the best balance/compromise, via the settings.cfg on user files' QVF folder.
DCS in VR is a SCIENCE.