For reference, I’m talking about my experience in Damnation Auric level and Maelstrom missions. Not talking about heresy and below, as I don’t play in those difficulties.
I played with surge exclusively after patch 14 where you changed it from a mass stun stick, to single target killer, and it felt great, it was in a good place. A staff with limited range and targets it could affect, but great single target damage (for most of the enemies).
You still needed a good blitz and melee weapon to fill the areas that surge lacked (bad horde killing speed and control) so overall it was balanced and could do the job in the highest difficulties.
Surge was supposed to be good at single target, but right now it fails even at one-shoting a simple scab reliably, because it is changed to randomly hit limbs, which of course does negligible damage. Not only that, but you cannot kill targets behind cover anymore, you might as well grab a purgatus instead, since you need to go and zap in melee range.
Also, surge received an indirect nerf, when you buffed the health of big enemies, like crushers. More health, more charge time, more time wasted to kill them.
Furthermore. even when the bugged +120% damage increase was introduced, a veteran or ranged focused ogryn could clear entire columns of elite gunners/specials, before surge could fire off a single charged zap, it wasn’t THAT much of a game changer or overpowered as some people claim it to be.
And before you go “but surge doesn’t have ammo”, let’s not pretend that veteran’s scavenger aura doesn’t keep you topped up in auric/maelstrom, ammo economy is a non-issue with that aura.
It seems incredible to me that a veteran can two-shot a crusher with a revolver in 2 seconds max, and he gets one ammo back, but a surge staff that required 3 full charges (sometimes four, depending on how many enemies you had to juggle) that took at least 4-6 seconds was considered too OP by some people.
TL:DR Surge needs to go back to how it was in patch 14 and have a 50-60% damage increase, for the targets it can hit/affect and the peril it generates, which translates to time it takes to kill/vent, it is vastly under performing in auric/maelstrom missions, other weapons are way more overpowered than surge ever was, even with the damage bug.