I wonder how a Gyro/floating gunsight would be of any use in AH.
I read the manual for the P51 Gyrosight, and to get the correct deflection, the P51 pilot had to follow the turn of his tgt for a few seconds. While doing this, he ajusted the sight, so that the triangles showing in it exactly matched the size of the tgt. After all those ajustments, that take everywhere from 3-10 seconds, the sight would give the proper lead. And during the process the tgt must never leave the area of the gunsight, so this doesnt work against tgts using break turns, barrel rolls, scissors etc.
Now where in AH you have a tgt that flies 3-10 seconds the same turn?
I hardly cant imagine anything, beside an afk climber or a suprised tgt, but than you are able to use a 0 degree def shoot from dead six.
In all other cases of snapshot or deflection shots, you dont have enough time, you simply have to guess were to point the guns and fire.
And finally, when you flying a bird armed with 0.5 cals and you are not capable of 500 yrd 70 degree def shoots, you simply have to spent more time practising. Or just jump into an LA5 or FW190 to learn to shoot with there 20 mms, if you than get back to the 0.5 cals you have no need for a gyro/floating gunsight.