More of an observation than a serious discussion topic, but I've realized that given it's new statline and general alterations in the game's combat engine, it's suddenly making a lot of sense that the IG would be equipped with lasguns rather than anything else.
Before (as in, in previous 40k roleplaying games), it only made sense from logistics' point of view - lasguns are cheap, reliable, and you don't have to keep megatons of ammo in stock to maintain battle-readiness. But dear God, were they useless from the perspective of the poor guardsman expected to fight Orks with it. Less damage than autogun, no sweet full-auto, and way, way worse special ammo types. It sufficed to shoot down some underhive gangers or a human riot, but against anything more ambitious, they were woefully inadequate.
Not so much in Black Crusade. First, one of their biggest weaknesses in previous games - namely, lack of full auto - is suddenly a boon for those poorly trained guardsmen, as under new rules, they're unlikely to hit the broad side of a barn while shooting on autofire. Semi-auto setting still lets them lay down suppressive fire when needed, and they still get a sporting chance of scoring this extra hit occasionally. Second, new firing modes give lasguns much greater flexibility - shoot in normal mode when it suffices (and enjoy vastly greater ammo capacity than any autogun), then switch to more powerful modes when necessary - in a pinch, you can pack quite a heavy punch. New Hot Shot Charges are also much better - it's still just one shot, but now it's a shot dealing more damage than a human-size bolter! And lastly, lasguns now deal the same base damage as autoguns. Being a guardsman isn't so bad after all... okay, I'm lying, it still sucks, but now you get at least a sporting chance against tougher enemies.
In case you're wondering, SP guns still seem to have their place in the game, thanks to the autofire setting (not good for Guardsmen doesn't mean not good at all in this case) and a wide selection of good ammo types. Any combat specialist running on a tight budget should appreciate them.
So... if someone wishes to add anything, feel free.