AH B17 has all guns in same convergence and the gunners can shoot through fuselage.. That means there is always an unrealistic amount of fire being shot at the fighter.. This aspect is porked in relation even to all other buffs in AH. It's time to get it fixed.
If the gunner is good not even slashing attacks or especially high speed ones will save the attacker. High speed attacks are murderous for the reason that the attacker can't manouver much during the dive if he wants to aim anything and that makes him an easy target for an experienced buff gunner. Try attacking a b17 with a 262 at 600mph and see how many pieces of you will fall to the ground

In reality the gunners in a bomber were not acting as one robotic unit but actually all tracked individual targets and also missed targets flying by even if the rear gunner was tracking him etc..
In real life a B17 or B26 couldn't outturn the top-of-the-line fighter that was attacking it, especially if he wanted his gunners to be able to shoot at anything. Now a 20k b26 can outturn a 262 making a vertical attack from below and actually gain separation on it if the 262 tries to follow to the turn. During and immediately after the turn the bomber can also shoot accurately with all its guns.
So the net effect is that a single bomber in AH is probably about as leathal as a full 'box' of bombers were in reality. Also the effect of bombing of a single bomber is greatly bigger than in real life. That is also why people do suicide attacks from 6 - they know that if they spend time climbing to a position enabling a slash attack the bomber will have laserbombed its targets - which means the defender already failed in his job.
The net effect is often better if you just attack the buff dangerously, ping him a couple times and force him to remain in gunning position instead of letting him release his payload.