Did a bunch of math related to this concept. After a little toying around with the math and charts I came up with this;
Essentially each surviving bomber rolls a D6 against the enemy vessels AV, and for each point it meets or exceeds the Armour it does one point of damage. So a bomber against AV5 would do 1 hit if it rolled a 5, and 2 if it rolled a 6. Comparing the 'best case' scenarios for the official rules (accounting for turret suppression), vs this system I made a chart;
The Red is the system I came up with, the Black, the Official system.
The nice thing is that the damage caused is modified by the AV in a similar way as official, meaning against 6+ armour the hits caused would be reduced by 33% from official, this mainly only affects Space Marines and Necrons. With the latter, this is an easy fix (reducing their inherent AC defenses appropriately), SMs.... I am unsure how this would be dealt with, 33% albeit significant, likely won't affect their win ratio. In fact it is reasonable, as their short range means they would have trouble against the 'lurker with AC' type player.
Against AV4+ it would be 2x the number of hits, which is a little more than the 1.5x, but this only really affects Orks, and with the improved turret values they fare a bit better.
It completely removes the 'double-affect' of turrets, and makes bombers fairly consistent. Doing what we wanted them to do all along, fewer hits vs. low turret things, and more vs. high turret things. Quite possibly the best thing, is that the damage roughly remains the same for the most common number of turrets (2).
Now I know that someone will complain about the lack of need for 'Fighters Escorting Bombers'. However this is quite easily done. Turret suppression isn't the primary function of fighters in any Naval Combat. Their primary function is escorting bombers. Bringing up an older concept, you could easily implement the rule that fighters will only ever destroy 1 fighter (or 1 AC marker in a wave containing fighters), but they will destroy every AC marker in a wave with no fighters.
For Fighta-Bommaz you would simply use the rule that they do not cause multiple hits for their attack runs. So against AV5 they would cause 1 hit on a 5 or 6, instead of 2 on a 6. Reducing their efficacy there by 33%. As the Fighter Escorting AB thing would be wonky, you would simply make the Orks have Fighta-Boats, with speed 25. Possibly you would make the Ork ordnance only remove 1 enemy marker, rather than the whole wave (but always remove at least 1).
Resilient non-fighter AC would save for only 1 marker to be destroyed rather than the whole wave when a fighter comes around.
@Pthisis, Eldar would never re-roll their damage! They have never done this, the only benefit they get is that they are hit by turrets on a 6+ rather than 4+. Which increases their efficacy here perfectly fine.
