LoL, people get flamed for spelling mistakes but no one pounced on me for redundancy? I meant to say that if I have a 500kg bomb and altitude, a wirbelwind is an easy target.
Ah, yes that makes much more sense, I wasn't sure why you typed that twice, just figured you lost your train of thought mid post!

In terms of high alt dive bombing, it's quite difficult to accurately hit a moving wirbel from an alt out-of-range of the wirbel's/ostie's guns. Most GV attacks from the air that I've witnessed have been very low alt.
I know this isn't much of an answer for a lot of people, but (like I said earlier) it really encourages cooperation between aircraft and GV's! The most effective base takes (and most fun!) I've ever seen have been when both aircraft and GV's go in to take a base. Aircraft protect the GV's, GV's can clear aircraft's 6's, aircraft can bomb/strafe GV's, GV's can shoot aircraft, aircraft can shoot aircraft, GV's can shoot GV's... etc etc...