I don't really know how one would get numbers for any of the above one way or the other though.
I am almost never IO blocked where the performance difference between the two matters. I guess when I do the initial full backup image of my drive, but after that, everything is incremental.
This doesn't make sense as written. I suspect you meant to say "SATA SSDs" (or just "SATA") in the first sentence instead of "SSDs", and M.2 instead of NVMe in the second sentence. This kind of discussion is much easier to have when it isn't polluted by sloppy misnaming.
Even then, I suppose it how the m.2 vs 2.5" SATA mounting turns out depends on the specific system. E.g. on this PC the main NVMe slot is above the GPU but mounting a 2.5" SSD is 4 screws on a custom sled + cabling once mounted. If it were the other way around and the NVMe was screw-in only below the GPU while the SSD had an easy mount then it might be a different story.