Ok, I wouldn't want to get into a fact-contest with you war buffs... But I heard somewhere (I think it was the history channel) which said that the Tiger's gun was so huge that it will literally kill itself it tried firing while charging, so it usually did a complete stop before firing...
Unless at some angle that would severely damage the suspension by recoil I cannot see that happening in any way, shape or form. For example, an A-10s GAU-6 produces 4 tons of reverse thrust, enough to stop the plane in mid air with a burst longer then 8 seconds, and the structure (aluminum) remains intact. How on Earth would it kill itself more then, at the most, throwing a track?
Bobby Woll, Wittmann's gunner, reportedly did it on multiple occasions. Given the 140 kills with Woll as the gunner, you have a good chance of that being true. Also, what do u think the point of gyro-stabilizers were? Now I'm not saying this was an everyday occurence cause more often then not your wasting a shell firing on the move at longer ranges, but to say it didn't happen or wasn't possible seems illogical.
Firing on the move is quite possible in FH2, you just have to understand the physics on shooting something either moving perpendicular, parallel in the opposite to you, or stationary. If hes running alongside you its exactly like shooting from a stand still. It takes a good shot, but as I said, quite possible with experience. I did it in a PIVH on Goodwood less then a week ago, just like it was in FH1.