I'm OK with Frigates dodging missiles, so long as they can dodge. The problem with that motif is a fair number of them aren't actually all that good at dodging and have to either use direct-fire PD, shield tank or die. I've never been a big fan of the idea that missiles should be great hard counters for Frigates, but it's largely tuned all right.
I completely agree that the tuning of Energy PD is terrible for the most part.
I just revised my stuff for Burst PD; seems my last formula didn't quite provide for burst ratios correctly, and was over-valuing their TTK.
So... after revision, if we're using OP's as par, with my current weight for range values, etc....
Burst PD, at 600 range, could have a base damage of 200/second, cost 61 Flux/second, and fire bursts lasting 0.2, with 0.2 delay, no bank.
That means it's really doing just 40 a shot, but costs only 12.2 to fire; this is fairly efficient and it's what we'd expect given the other ratios, range band, etc.
A Burst PD gets 2.5 shots / second, so it's only going to get about 4 hits in, for 160 damage, before a typical missile hits the ship, unless the ship's back-pedaling at maximum speed. So, that kills one Harpoon (150 hitpoints) or two Annihilator / Swarmers (50 each), with maybe one shot to engage another one, but might turn into kills on 2 missiles when backing up.
This makes it more efficient, Flux-wise, with where the PD Laser ended up, and with slightly more range, but you get that efficiency at a significantly higher OP cost.
To make the Burst PD more effective, the option there is to either bump range to allow more engagement time, or bump damage up but lose some Flux efficiency. I'll probably go for the latter; I figure if you're mounting a 7-OP weapon, you're probably OK with it costing more Flux, so long as it does its job reliably. 2 hits to kill a Harpoon sounds about right, so we're talking 250 base damage for 95 Flux, which is reasonable (these numbers sound outrageous, but bear in mind that the weapon's not in continual contact, suffers the SS 1.5X hard nerf against Beams, etc.).
Heavy Burst PD is now at 400 base damage; not quite enough to kill a Harpoon in one hit, but two every time. 800 range, so that it's in its own range band; 205 Flux; it's not as efficient because of the range.
Guardian's the only one where I can't justify it and I'm not sure it can be fixed. For 22 OPs, you get a 900-range burst-PD weapon that does 500 base damage (i.e., 100 per hit) at 180 Flux. It's very efficient, even at the range, but the cost in OPs is outrageous for what it does.
I still think the right answer is to put Guardian into Medium, lower the OP cost to 15, give it the range and make it less efficient. The numbers on that: 15 OPs, 500 base damage for 265 Flux, 900 range. It still won't kill Harpoons in one shot at that point, but it will kill Hammers in 4 shots and Reapers in 5-6, so it's probably worth using.
I'm tempted to boost the base damage a little higher than that, so that it's capable of dealing with Squalls and two incoming Reapers; if it could do that and was Medium, I'd probably actually consider using it on High Tech ships.
So, what does that look like?
750 base damage (i.e., 150 per pulse, or enough to kill a Harpoon in one shot) for 595 Flux, or 119 per pulse. That's pretty high Flux output- it's massive overkill for killing, say, Annihilators, and will be a waste of Flux then.
But four shots to kill a Reaper sounds about right; unless the Reaper's launched at point-blank, the Guardian would kill one of them at least, which would be 476 Flux down the drain to avoid taking 2000 Hard Flux (in the best-case scenario). That sounds pretty reasonable, even if often even that much firepower wouldn't suffice because of time-on-target issues.
So there ya go, folks; burst-PD numbers that actually make some sense. None of these numbers turn these weapons into amazing assault guns, either; they're still Beams, with the penalty against Armor damage, Soft Flux against Shields, etc., which is all factored in.