That is what I have moved to. My OS drive and the main work drive are now both very fast m.2 drives with a new 4TB SSD as the main internal storage/backup. An older spare SSD dropped in just because it's there and the only spinner is the main external "grab and run" backup drive that everything is copied to. Apps are much faster and my service to the house is 400/25 so when Norton isn't choking things everything is lightning quick.
I sure have, always used m.2 for my OS drive. I am currently toying with popping in my spare 256Evo SSD as a quick and easy scratch drive for tempory editing storage. then archive over to my spinners.