That Canadian sniper is my partner who works for Triple canopy's former roomate.
As for the endless 5.56/9mm vs 7.62/.45 debate, my partner in my private military company here who is currently stringing out to TC in Iraq has shot numerous people with 5.56, and a couple with 9mm, with most of these shots resulting in immediate incapacitation and then death. SHOT PLACEMENT + Blended metal ammunition (still semi/sorta classified I suppose) = massive trauma as well as armor penetration capability unlike the world has seen in small arms.
He's emptied his ready-gun bag, which is ten magazines, and shot many of the mags in his load bearing equipment, and has yet to have a malfuntion in his M4. Same goes for the M249's. I think the reason you see such a disparity in the reliability and lethality of the 16/m4/5.56 between private contractors and regular army is that the army/marines are out in the dust and dirt a LOT more, and their accuracy is usually some percentage points behind that of the special operations community, whose members comprise large numbers of the private companies ranks.
My personal rifle is a Socom Springfield M1a, basically a cut down m14 with a rail system and other crap. I'd prefer to shoot my Valtro as a sidearm, but the two companies I do work for use the Glock 19, which have proven to be ultra reliable (with ultra gay triggers) in the desert, and the Sig226, which, obviously since I'm instructor for Sig, I swear by. What I'm saying is don't shoot the messenger as I prefer .45 and 7.62 myself, BUT 5.56/9mm is proving plenty lethal in Iraq. I'll link an article a guy from Blackwater that I know wrote specificaly about this issue once my canadian gun site is back up.