I would say, more accurately, that each weapon has it's own job.
On the topic of super sniper rifles though, i like a suppressed, best quality, manstopper/toxic round using SP sniper rifle, personally.
The only reason i'd use a triplex or long las is for the felling.
Though when you think about the amount of damage you can deal with the Accurate trait and taking talents like Crack Shot (whichever it is that increases critical damage for ranged attacks) even Orks aren't much trouble to drop.