Does M2 really makes a difference for load time? I as assuming we are discussing M.2 with PCIe interface. I did Youtube reviews before my recent new computer build and found benchmarks might show M.2 are faster then SSD but load tests of boot and program load times are only a few % faster, thus for me was not worth the near 2x in cost. What delta do you see in P3D load times with M.2 vs SSD or HD?
This was my issue, disabled Acronis True Image's Active Protection fixed it immediately, I was stuck at 6%, disabled Active Protection and the load starting climbing and completed within a few seconds. Maybe this is related to another issue I had which was when Navigation > Go to Airport.... I would get a pop up saying Prepar3D cannot run because it could not write Prepar3D.cfg. Perhaps disabling Active Protection would fix this too.