The reason I brought up LD was because of the whole Recon CTR boost --> Max. I've seen my Biohazard at max CTR and was disappointed even just doing test shots in the locker room.

Cocosnake, if you're soloing, do whatever feels good to you - none of this stuff really matters lol.

...but if you're in a party, relying on charge shots is generally a terrible idea since your sword-using teammates still kill faster and will eventually run into your tagged monsters, start knocking them around and screwing with your aim and timing. More often than not, you will only shoot one charge before deciding to detonate, purely out of practicality.

At some point, you will start using something to boost your gun damage- and you come to the realization that catalyzer's charge shot isn't affected by damage boosts (or penalties) at all. At this point, you start wondering when you should EVER use your charge since you can kill at least 3 monsters in less time using your normal shots, since they get benefits of the damage boost.

There's an interesting balance between CTR and ASI here :
If you have CTR, your time BEFORE the shot decreases noticeably.
If you have ASI, your time AFTER the shot (well really, the whole shot) decreases more noticeably.

When is a gunner vulnerable? When it isn't moving. When aren't you moving? When you're firing the charge shot.
ASI helps you shield, move, and (gasp) start charging again earlier.

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Anyway, now that I've made the case for why faster attack speed is better for gunners...
you can run around with gear that boosts your attack speed by a bunch (hi swiftstrike). I did a silly test just now equipping and unequipping swiftstrike - the charges-per-second jumped noticeably more with it on.

...But if you run around with ASI gear, then it's only redundant to have extra ASI, isn't it?

So, looking at the gunner sets... I think this is the real issue:

Are you going to be wearing ASI-boosting gear or damage-boosting gear?

If you're going to be wearing ASI equipment, you're better off having some CTR on the gun to keep some balance.
If you're going to be wearing damage-boosting equipment, you're better off with ASI on the gun to feel more useful. You're absolutely wasting your damage-boosts trying to buff the catalyzer charge (no effect LOL) anyway.

PS.
Biohazard is the usual choice since jellies are easy to tag with charge and it does extra damage vs jelly.
The only reason to get neutralizer is to use it versus zombies. They're the only other thing slow enough to really mob well. (...but then you could kill faster using an elemental gun...)