Ken C, you are seeing consistency in answers. I have experience with a couple of Smith Enterprise mounts. They are very well made, have adjustments to fit with the differing receiver dimensions and stay tight. Sadlak works well too. ARMS is too low on some rifles. There are reports of ejecting cases bouncing against the top of the mount and back into the action, jamming. Grinding out the center portion to make it like the old version works well.
Aluminum mounts are mostly are junk, including Springfield's. I went to aluminum mount way and was sorely disappointed. One worked loose every six rounds. With locktite it lasted one magazine. With others the aluminum flexes and won't hold zero over any length of time. An M1A has severe vibration compared to most other rifles. An M1A is the best of rifles, get a first rate mount like a Smith or Sadlak.