Burst PD might be somewhat less flux efficient and have less dps than tac laser, sure. But:
1)It has better burst capability (esp with expanded magazines, which are good idea if you combine burst pd with autolasers). Beam pulses also have high (not sustained) dps - it goes through armor easier(not too much on fighters, but there is some)
2)It doesn't waste time on rotation. Tac lasers actually waste a lot against fighters.
3)Having good pd allows you to drop shields more frequently - more flux to fire weapons/less hard flux accumulation threat. +Intercepting missiles with pd costs soft flux, tanking it with shield - hard.
With that said i actually rarely use pd on smaller ships (they can dodge/have easier time flushing hard flux on demand). It is mostly useful for capitals.
On Hyperion:
Actually pretty much anything with speed about 150+ speed will get behind Onslaught even under AI-control. The only question is whether it will fail to manage it's flux & die to backward facing guns or not
. Ai-Tempest also can solo Standard Onslaught if you add it extended shield (without this mod tempest will die to flak).
Player-piloted Hyperion can kill anything, even Paragon, it just takes time. AI is quite good with it, but does make serious mistake. Best Ai-piloted build in my experience is one with Burst pd - it is the only weapon which can reliably bypass omni shields even in AI's not so skilled hands. + It's flux-cheap which prevents them from dying due to flux mismanagement.