Hi. An M1A doesn't count. It's an expensive, commercial, sporting rifle that has been raped by the SA. Inc. marketing Dept. Their silly SOCOMs etc., are marketing things.
"...missing anything by not..." Wouldn't go as far as saying that. FALs weren't cheap when they weren't evil. $300 plus, as I recall. Pay scales being much different then and now. $300 was a lot of money, 20 years ago. Would have had to sell something important to buy one then. Mind you, I got to shoot C1A1's for pay then.
Can't say as I miss not owning one. Not being able to shoot one without a lot of fuss is another thing. They're neat, but only because they're real battle rifles that are a piece of history. Except that Kingston is a long way, the ESSA open house(Juneish), might provide an opportunity for you to shoot one. Operative word being 'might'. Contact Stormbringer.
"...The FAL is a more modern design..." Than what? The FAL and the M14 are contempories. The U.S. tested 'em both when they were looking to replace the M1. The FAL won every test, except accuracy. The M14 was adopted for political reasons, not because it's a better rifle. NIH raised it's ugly head. The M16 was adopted for political reasons too.
"...liked the rear disk site..." Always thought that was a weak point of the C1A1. Thought it'd be easily broken off in combat. Fortunately, nobody had to test that.
"...it bruised my cheek..." Butt stock was too short for you. Mind you, I found that not all of the 'normal' butt stock lengths were the same. Had one on my MIU that was perfect for me, but not all of 'em.
"...Obviously I'm missing something..." Better FA control. More natural angle for the hand too.