Therein lies my delima. I too have been studying this for awhile. My thoughts were, as time goes on, the FAL is going to become more and more obsolete. I do have 12 mags for it.
I have thought about the Springfield M1A, and have heard a little bad news about it due to Springfield cutting corners and getting them out so fast.
I thought about the Rock River version. I have found FAL metric mags for $18-20 (used) on the internet. Eventually they will dry up.
I thought about the Armalite. Don't know how to make the M1A mags fit?
So, that leaves the DPMS, Remington, Knights, and Larue which you mentioned. I also didn't know the Army was using this platform. They also use the Magpull mags which are aound $18 but are on backorder most places. Also as you said there are other uppers for them.
My thoughts were as things are going to standardise on the two platforms, AR-15 and AR-10, buy various uppers for various calibers. Buy replacement parts. That being said, I could hunt just about anything in North America.
With the AR-15, I can use a 22lr adapter in my 1/12" twist. I can buy 6.8 SPC, 6.5 Grendel, 50 Beowolf, 450 Bushmaster, and maybe a few others.
With the AR-10, I can use the 243, 7mmO8, 260 rem, 308, 338 Federal. Maybe they might make a 358 at one point, but the 300 WSM sounds intreging.
Just get the right upper for the various hunting conditions, buy some 5 round mags for where that might be the legal limit. But, you know what, the 223 and the 308 with the right bullets and loads could hunt anything in North America without changing uppers.
I just wonder if DSA arms is going to continue making the FAL rifle? They should make new mags if they do. The FAL is rugged, but the AR-10 platform is more accurate and has more parts availability with just a few tools to work on it.