Guys, my points are purely about game balance
Honda, I still have nightmares ÂÂ

 about the "5 aces" use of AX-0-1 for 175 each against my Eldar and Marines. As Hena says, with 45cm weapons all round they easily suppressed or destroyed all ground AA, and were tough enough to ignore most CAP (except nightwings as I recall) - and the results were brutal to say the least.
Hena, regarding paired WE there are two related issues relating to the survivability of the formation.
1) You need to kill 4 points of aircraft, where most AA usually only gets 1-2 hits. As these are spread out over the formation, this is not enough to stop both a/c from completing their mission and indeed may not be sufficient to stop them returning next turn.
2) DC2 aircraft can fly 10 cms apart which potentially allows the rearmost A/c to shoot any enemy attacking the front A/c. This in turn forces enemy CAP to be positioned such that any hits are allocated to the rearmost A/c first. Assuming only one hit was scored in a previous turn, by putting the damaged a/c in front, it makes the formation that little bit more survivable. Not game breaking in itself, but it does mean that a pair is more durable than two singletons