Couple of questions that aren't clear:
Does the specialist equipment - e.g. a Heavy Gunner's heavy bolter - become part of the Standard Regimental Guardsman Kit?
Or is it part of the Mission Assignment Gear?
I'm curious as the Standard Regimental Kit doesn't mention specialisms - and it makes the mission assignment logistics test a lot more important if your weapons specialist (for example) might not get his meltagun.
Second;
I understand weapons specialist having access to the meltagun, shotgun, and flamer, but what is the point of the lasgun?
He will get a lasgun (or lascarbine, or whatever) as part of his Standard Regimental Guardsman Kit, so this essentially means he'll have two.
Secondly, a good quality lasgun makes no difference whatsoever - lasguns are reliable by default, and I don't see why squad member X would be issued a non-standard basic rifle.
I can understand the weapons specialist being the squad marksman, or whatever - but in that case I would let him take a telescopic scope, or an auxiliary grenade launcher, or whatever, that he could fit to his existing lasgun, or else give him a long las.