From the PoV of an infantry spec in the unit who has used both the SAR and the M16 in unit exercises,
SAR sucks. Nice concept, but it's implementation stinks until someone bothers to refine it. Maybe I'm a biased left hander.
WeightThe SAR is considerably heavier than the M16. The weight difference might not be much when you first hold it, but try holding it in extended missions (above 10km), and it's a literal pain in the neck with a rifle sling. While it's not as heavy as MGs and stuff, we are expected to do rapid fire movement with the SAR unlike the MG team.
ScopeThe SAR is useless in rainy weather and muddy terrain. Rain water or mud could splash onto the front end of the scope and obscure the view. The same could happen to an M16 too, but the front of the scope is made of glass material and is harder to clean compared to an iron sight. You might be able to clear off the mud, but you'll still get a pretty blur view. Rain is a bigger problem if it drips onto the iron sight, because if it doesn't stop, it's pointless to wipe the scope.
Iron SightLocated on top of scope. I suspect this feature is a joke by ST engineers. It's completely useless because it's too small and you can't zero it.
MagazineInnovative. Made of clear transparent plastic with markings at the back that enable the soldier to see amount of rounds he has left. However, it's impractical as it is too big for the current SBO (by current i mean 1-2 years ago when I was still in the army) that is too small to hold 2 SAR mags in the same pocket. Also, the rings around the body of the mag will interlock with another mag further interfering with combat reloading. Major pain.
Immediate StoppagesWe were told the SAR IAs less the the M16. That's much is true. But when SAR does IA, chances are that it's a very serious one that cannot be cleared quickly (expended cartridge stuck behind bolt carrier). You might even have to strip the SAR to clear it. I'll rather choose the M16 that IAs more than the SAR that might not be able to recover from IA.
InteriorWhatever material they used to make the inside rusts a lot easier. My SAR was only 4 months old, and it came back post mission with some serious rust. No, I didn't do water ops. Yes, it was clean and rust free when i went out with it. Maybe the SAR is still in the testing stage and I got some beta version? Personal hypothesis : SAF make these first versions with cheap metal, tests it in the field. After which they make newer final versions, and then sell the "beta" versions to other our neighbours.
Deflectors and left handersI'm a left hander, and I totally hate the SAR. I'm biased. Why? The SAR does not have a deflector add-on. They have some mini joke of a built in deflector, which btw is some small triangular piece of plastic. It doesn't do its deflecting job
AT ALL. During live firing, as would be the case during war, I get hit by like 90% of the bloody hot empty cartriges.
BayonetErm ... what bayonet? THere's nowhere to fix it on. Sure, in close range combat you could smash the enemy's head with the heavy rifle butt. But given the SAR is barely 1m long, you might not reach the bugger before he pokes you with
HIS bayonet.
Outer CasingSomeone told me the outer casing is made of Kevlar. No idea. Even if it is, SAR still looks like a toy. Anway there are claims that the SAR will protect the soldier's precious face in event of a chamber explosion as the casing and rifle interior can contain it. Means jack to me becasuse as a left-hander, my face is right behind the ejection port. If the rifle goes boom, the blast impact will go only where it can, out of the ejection port, to my face ...
Fire mode selectorThe bullpup design forces the fire mode selector to be positioned behind at the buttstock where the trigger and firing mechanism are also located. Tough to change fire mode during combat.
Other rare plus pointsSAR interior is easier to clean due to it's design.
Has a lighter recoil compared to the M16 (further making it seem like a toy).
The weight is evenly distributed making it easier on aiming.
The SAR has better accuracy due to scope (barring crap weather/ground) than M16 in close range.
Integrated LAD is nice idea.
Zeroing will remain no matter how many times one drops the weapon. Note: nobody in our unit was willing to test the claim by repeatly dropping the SAR during range.
Besides, if SAR is so good, SoF/STAR/SWG would have switched to SAR long ago.