I did use them succesfully to defend myself against a first round protoss rush, while i was teching to mutalisks. But they did go down the second round. (Although my mutas punished my enemy greatly for it. )

Scrouge are great.
Mutas are great.
The Zerg air track is the best air track.
Even though the Carriers and BCs can't easily be killed outside a base, there are only a few of them, and they come late.

This is also I think the silliest point of transistion from computer game to boardgame.

It seems to be one of the most jarring, technicalities of the SCTBG combat system that an non-attacking air-to-air suicide unit can hold of infinite waves of... zealots?

I'll get over it I guess.

I think the scourge are broken. An easy way to fix this is how you resolve retreats...see my thread here: http://www.boardgamegeek.com/thread/264385

This problem is corrected in the errata. The scourge cards should read as follows: "If your front-line unit was not destroyed, destroy it. If this happens and your opponent's front line unit is flying, it is also destroyed. This does not trigger any splash damage abilities."