Right, which makes it ... as powerful as an assault rifle, but more reliable. I don't think I've ever seen lasguns depicted as anything other than that.
Wait wait wait, source that for me. In what sense is flak armor wildly superior to anything modern society can even conceive of putting on standard infantry?
I'm going to have to disagree with you on bolters being the equivalent to modern anti-tank weaponry. Are you talking about man-portable ATGMs?
Source?
I'm perfectly willing to move the conversation out of Sororitas territory, since that gets into weirdness that has no StarCraft equivalent.
The technological scale of 40K is anchored, for me, by a couple of things. One is the lasgun-autogun equivalency. Autoguns are consistently depicted with capabilities and mechanisms equivalent to (and in some cases, inferior to) modern assault rifles, and lasguns are consistently depicted as having equivalent lethality. There's obviously some wiggle room in there, since "modern assault rifles" describes a range of lethalities, but I haven't read anything to suggest that a lasgun is materially more lethal than what we use today. That is, of course, quite lethal indeed, but the fact that a lasgun can stop a rampaging space marine or ork with a single shot says more to me about the realities of wounding mechanisms than it does about the over-the-top firepower of a las bolt.
Another anchor for me is the Earthshaker cannon, which we know is a 132mm weapon with an effective range of 15 kilometers. That is, [url=http://en.wikipedia.org/wiki/M109_Paladin]as you know[/url], not impressive at all. And yet this is a front-line weapon for the Imperial Guard. While it's true that we don't have any hard data (that I know of) about the explosive yield of an Earthshaker's shell, the specifications we do have are distinctly substandard by comparison to equivalent first-world hardware.
Back to StarCraft ...
The point that I'm making is that the destructive scale of StarCraft is not, as I understand the fluff, very different from the destructive scale of 40K. Yes, it takes an upgraded marine six bursts to put down an upgraded zergling, but we should take that with the same grain of salt we take the fact that a space marine needs 2.25 bursts to put down a naked human being. Fluff-wise, StarCraft has its own autogun equivalents, which are definitely depicted as being seriously inferior in firepower to a marine's coil rifle, and which are definitely depicted as being essentially impotent against marine power armor. That is, I submit, the essential relationship of the autogun (and thus the lasgun) to 40K power armor as well.