I am doing high CZ with just Executor and Tormentor doing 4-6mil per battle. I rarely hit a target more than once because it is either a kill or my team mates finish it. Finding a good position is the key to use the Executor correctly, but if you are used to the shotgun it might be different than what you are doing. Enemy sharpshooters are devastating at high CZ.
I just tried the G5 Executioner in a high intensity CZ and it's as I thought it would be: 1 shot shields, 1 shot suit. Still, in my opinion, easily the most powerful and versatile weapon in the game, but obviously still with a much higher skill cap. I can't say it needs to be changed much.
But, still... When people call this a sniper I just disagree. It's not a sniper. Not by any sensible definition. Using it at long range is a matter of fortune most of the time (and sure, I've landed some pretty amazing long shots but that's definitely not something I can claim to manage consistently). It's a short-to-mid range assault weapon. At mid-to-long range it's deadly still, just less so against moving targets that are moving laterally (but that's something that absolutely will change with experience and skill and so this is a good thing). The only reason it could be called a sniper is its damage at long ranges is the same at close range (still 2 shots). But a sniper should be
most effective at longer range. This is most effective at anything
but longer range, deadly at close range particularly with extended magazine.
Two hits to kill a fully upgraded target is something very few weapons can match and the Exectutioner pretty much enables this at G3/G4 (my G4 exe still does high intensity in two hits so...) I don't think the "overdamage" is necessary. It's just two shots and the idea that one only takes away 1% shields is sort of irrelevant... If it bothers someone then just pack the plasma pistol to strip shields then switch. If a G5 executioner somehow took 2 shots to take shields down against high intensity targets then I'd agree that would be sucky, it'd be quite weak in that case. It doesn't and so... moot argument I think.
Ultimately, this weapon takes an annoying mechanic (bullet sponge, weapon switch) and negates both. So it'll always be my favourite weapon.