I think the spider AA is too good for the price.

Tarantula : Damage 1200, well... it can also utilize terrain to avoid damage while shooting tracking missile at a max range of all mobile AA... and cost 1500 less than other 2 advanced AA. and it is faster than archangel

It is a supreme unit among all AA units IMO.

It should get price up a bit, I suggest 450.

Jumpy aa still is best ;) Spiders shot slowly.

Its extremely accurate AA missile (110DPS/1000Range)can shot from behind a hill or from cliff. In regards to this and the value of all-terrain move type. 400 is cheap enough.

But yet, its fire power lower than archangel when close-in, but the damage it deals are probably greater. no turn rate. One shot a blastwing or a gnat, make the difference; and higher damage for single shot.

I think it's fine balanced - not compared to static AA, but good else.

Vandal is well balanced against bomb drones and get some benefits if you spread them ( Black Dawn don't hit more than 1 at a time if you use them wisely )
Jetro is also good against Black Dawn, and a bit more effective against gnats, because of less overkill.
But both - Jetro and Vandal have only very low dps/cost.

Flail and Copperhead are both vehicles - they can only move cliffs where other vehicles can do it to.
Flail is fail ! - at least against bomb drone spam and gnats.

Archangel cost many metal at once and can't hit well with it's 1000 range autoCannon - but once a target get's close to 800 or 700 it hits it with pretty good dps/cost.
Also Archangel is kind of AT because of it's jump ability and can jump out of BlackDawns missles once or twice ( at the third shot ).

I think Copperhead is the BEST mobile AA, followed by Archangel with it's high mobility but less effective range.
Also Copperheads shot aren't as visible as the shots of an Archangel - causing enemies to waste a few seconds before they retreat.

So I think Spiders with 400 metal have good stats now.
If you want to nerf them against AIR ( not gunships ) nerf the HPs a bit so that they die to one precision, instead of survive one hit with only a few HPs.