Been doing some more weapon testing with the 'best' (read: highest impact) model of gun of each primary weapon type. I don't get pulse rifles at all.
Suros JPS-32 pulse rifle with just slightly under 50% of an impact bar:
Precision shot = 78
Body shot = 24
Clip size ranges from 21 to 27, but of course that's really only 7 to 9 bursts. Stability is pretty much exactly 50% on my gun, and even with it that high it is completely impossible to land three headshots from a single burst. The up and left pull will make the last shot miss every time, so you have to start with a low-right shoulder shot if you want all three to land. Best case scenario you do 180 damage per burst. If you just want to dump the entire clip with a pulse rifle--good luck hitting anything--it takes about 3.2 seconds for 8 bursts with a ~15% ROF bar. Oh, and that's with a gun that has the "Causing damage with this weapon increases its stability." mod. Yeah, sure it does...
Now compare that to a Cydonia AR3:
Precision shot = 113
Body shot = 38
Cydonia ARs have about a 33% impact bar, and they still do more damage per shot than a pulse rifle. Stability is the same, except that the AR isn't limited by a stupid burst that pulls way too much and you can put every single shot into the head if you're any good at aiming. Clip size is 24. Three shots with an AR does up to 339 damage with good aim (easy to do in my experience, and I bitch more than anyone about how bad gamepads are for FPS). Dumping the whole clip with Cydonia's 80% ROF bar takes 3.6 seconds, and unlike a pulse rifle you can actually control the shots.
My conclusion is that, much like how there's zero reason to ever use a hand cannon instead of a scout rifle, pulse rifles are completely worthless next to an AR.