I am a B25H "frequent flyer"... and here is how I use the F3, and my thoughts on its use in general.
I use F3 to get a look around my plane while flying. To spot aircraft around me and to spot vehicles on the ground. I have NEVER used F3 when on a bomb run, or when firing any of the guns, whether it be the forward MG's and cannon, or the turrets. I dont even see how anyone can aim that way. I am sure there is a way... and perhaps it is easier, but I have never tried it, nor do I care to. And didnt know you could use F5 + F8 in the air
Hehe... learn something new every day!
Anyway, if I am on an attack run, or engaging in air to air combat, I am always in F1 mode. Call me crazy, but those gunsights are there for a reason.
I fully agree that no guns should be able to be fired, or ordinance dropped from the F3 view. But restricting the F3 to "4 engine bombers" as opposed to "2 engine" doesnt make sense to me. There is no way to fly the B26, B25, the Boston, or the A20 in F1 and be able to tell what is around you the way a fighter can.
F3 is available to planes with multiple gunner positions to simulate the ability for other crew members to see what is around the aircraft. Without this capability, the A20, B25, B26, and Boston would become hangar queens, and for no reason. They are outstanding aircraft.
So... here is my opinion (for what it is worth) on the F3 view and its limitations in the Main Arenas:
1) Can only be used to look around the aircraft
2) Weapons will not fire and ordinance will not drop in F3 View
3) No zoom or ability to alter field of view should be enabled for F3 view.... make it a fixed point of reference.
4) F3 should only be available on aircraft with more than one gunner
Now... I can hear the SBD and IL-2 drivers already screaming about #4. So... here is what I propose:
Give them the ability to have their "rear views" to be seen from the rear gunners point of view instead of the pilots. This can be done by allowing them to "zoom in" past the pilots seat into the gunners seat when they are setting up their views. Then they save the view and they then have the ability to see what is directly behind them (and on their rear quarters) without the wings or the back of the pilots seat being in the way.
Doing this would still give the 2 seat planes a better view than a single seat, but they would not have "multiple sets of simulated eyes" looking around the plane as a bomber with multiple gun positions does.
Anyway... those are my thoughts.