Alright, so after session each of Assassination/Massacre stacking and bounty hunting, here's my consolidated feedback.
Just some preface, if I refer to an increase or decrease in reward, I'm referring to per-ship kill. This is obvious for standard BH stuff, but for missions less so.... if you didn't know, massacre missions reward per-kill, so a 40 kill mission will reward twice as much as a 20 kill mission. If I say "Reduce number of targets", there's an implicit reduction in total reward, but the per-kill ratio remains the same, so it's not actually a reward reduction.
Secondly, I will distinguish between "massacre missions" and "CZ massacres", as the two are very fundamentally different.
With that out of the way....
Wing massacre missions: Halve reward, Halve number of targets
Solo massacre missions: Quarter reward (yes, reduce them compared to what they currently are), Halve number of targets
Wing and Solo CZ Massacres: Fix the bug where Wing massacres have a higher per-kill reward than solo
Solo CZ Massacres: Halve number of targets (after fixing reward ratio)
Wing CZ Massacres: Halve number of targets (after fixing reward ratio)
Assassinations: Good change, leave
Wing Assassinations: Double reward (8-10m for Allied)
Bounties for Vanilla Kills: Keep as-is
Bounties for Engineered Targets: Quadruple payouts
Basically, the factor that's gone completely unconsidered is the stackability of Massacres. A single massacre mission now offers roughly 1m per kill. Lightly stacked that approaches 200m for per fifty kills of any ship type, and that's not even considering the bounties on top of that which stand to up that to around 50m, 100m if you include some Powerplay bonuses.
But the enhanced payouts work for CZ missions as they do not stack, except in the case of wing missions.
By reducing payouts and number of targets, stackability (which is where the excessive payouts come from) is mitigated, but the missions themselves become easier to resolve, lending themselves more to comparable game activity loops of around 10-20 minutes effort. I'm less fussed about Wing stacking, bully for you for getting mates into the game tbh... in lieu of some high-end dungeon-like thing/scenario to do.
Wing Assassinations are in dire need of a buff... for the effort involved (usually a wing of 3-5 fully engineered targets) they're woefully underpaid at 4m credits, compared to the mission I did recently to kill 12 vanilla ships (which I easily did in a ship not optimised for fighting) for around 17 million. Around 10m for a Wing assassination, when you also consider the next proposal to buff bounties on engineered targets, would bring a single wing assassination up to a total payout of =~ 30m. Considering the effort and difficulty of that compared to a comparable reward from massacres, that's pretty balanced.
New bounties are pretty on-point, but Pirate Activity Threat 5&6 payouts, and other engineered targets such as for Wing Assassinations are ridiculously low by contrast. These should be the premier bounty farming environments, not everyday pirates in a civil liberty state. Remember, PA Threat 5&6 only exist in Civil Unrest/Lockdown, so as people swamp these for the premium payouts, it will self-terminate once security increases again, so if engineered targets pay out signficantly more, it's only for a temporary period until you need to relocate for more CU/L states (which are pretty rare, because Elite: Best Friends)