Re the sights on the handguns...This is being used by tier one operators who shoot upwards of 500 rounds a day. They start at extremely close range to the target (i.e. one foot away) and draw and shoot learning to index by looking at where they want the round to hit and squeezing trigger...a variation of hand eye co-ordination. I.e. you point where you look and you look where you point. Once they're synchronized you take the target out to two feet and progressively work it out further and further. I heard about it from a mate in a non existent unit and told another buddy in the local SWAT team I used to teach DT to and he said that they were now taping their front sights over and practising the same way. Again, I have to stress this is for extremely switched on buggers using gobs of ammo all day practising extreme close quarter battle techniques i.e. room clearing, hostage rescue etc.
You said that you also took off your front sight. Again, why knock them off your handgun. Are you putting in this much time each day!?
When you are at contact distance, no sight are needed. I agree, but there are time that the distance is reaching out there and it necessitate the precision of sights.
Disagree with you about patterns opening up at distances greater than 15 yards...depends entirely on who's doing the shooting doesn't it?
No, it doesn't depend on who's shooting. With the same person, same ammo, same gun: The reliability of hitting the same hole over and over will decrease due to inconsistancy in the same shooters. Sorry. physics will back me up on this one.
Re the no slings...Aussie army and brits do not (in regular line troops) use slings. Check pics of them on patrol in Northern Ireland, Falklands etc. Butt of the weapon is in the shoulder all the time so it can be brought to bear immediately.
Bad philosophy. A trooper will not keep the butt of the weapon is in the shoulder all the time so it can be brought to bear immediately. It won't happen. Your muscle will not allow you to do it....the weight of the weapon is wrong. The best that they will do without a sling (in the slow times) is carry it with their left arm supporting the rifle.
When I hunt hogs in the Texas brush with an AR15 (where the pop up at anytime to run away or toward you with ill intention) I can't keep the weapon at ready 100% of the time....you just can't physically do it (start at 6:30 in the morning and go till 7:00p and try it).
A sling can easily be adapted to be within inches of your shoulder and ready - I do this all the time when hunting hogs. Laziness has nothing to do with a sling. It has to do with the trooper.
The exception - as stated in my previous post - are hostage rescue and counter-terrorist units who practise transition drills from their "longs" to their "shorts" for speed reasons. I.e. it's faster in a house clearing exercise to go from a jammed MP5 to a handgun than to try and clear the jam. That sort of transition drill isn't likely to apply to regular troops.
I'm not buying it. The regular troops that the US has around the world are working in the crowds, houses, etc. and need the ability to transition to a backup gun without abandoning this primary battle rifle.
SAS used to use the SLR (aka the FAL) in 7.62 (as did the rest of the Brits, the Aussies and the Kiwis etc) They found their chances of hitting the guy on the run in the jungle increased with 00 in the shotgun.
In an "improved cylinder" barrel OO pellets will spread out about one inch for every yard of range traveled...
so at 75 yard... about a 75" spread with 9 (.33") pellets
If you want to talk general sprad to cover all the basesy: about 10 inches for every 15 yard (50" @75 yard)
However, consider the following:

I'm sure that the chance of a hit are probably better. But the balistics will argue the against killing velocities at 75 yards...
I've shot the FAL....great rifle, but not one that I would want to shoot people on the run in the jungle - BAR would be a much better option...but I'm bias.
Incidentally they dropped that weapon because they figured WWIII was going to be against the Russians fighting house to house. In N Ireland they'd discovered the round was so powerful it would go through multiple brick walls so they wanted a smaller round that didn't have the penetration of the 7.62
Now read about the Americans in Somalia shooting the drugged up "floppies" with the 5.56 and watching in dismay as they jumped up and ran away despite being hit with multiple rounds. The only one getting consistant one shot kills was an old Delta hand with an M1. As I've said before (and some here have disagreed) the bigger they are, the harder they hit!
I officially call all caliber arguments "out-of-bounds" - gentleman's agreement..this will bog everything down....
Back to the sight thing again. It used to be accepted doctrine (and in some schools it still is) that the focus during combat should be on the foresight while the rear site and target will be slightly blurred. What the more progressive buggers are discovering is that in combat you're going to focusing on the bad guy in front of you and not your sight..it's human nature and that's why these tier one boys initiated the change.
You should play round with it a bit. I think you'll be pleasantly surprised at how accurate it is.
I agree with the philosophy, and for the most part live by it. But, the forward sight is a very helpful tool for precision work outside of 10 -15 yards that has no need to be removed. It can become a hinderance from some shooters, this depends on the amount of training and their natural skills. Some of the time you will soft focus back to the front sight...but it depends on the situation.
I was working steel on Sunday at 10 yards with a 4" plate behind a "hostages" shoulder. Pretend that this was your wife of loved one (no offense meant) and you had one shot from a draw. Would you like the ability to have a sight to improve your chances.
I challenged each my four friends to this challenge this those words. Each took more time (a split of seconds) to engage the target the with the first shot of the day...and concentrated on their sight. All were good shooters all took the extra time...it counted.