Welcome to the Mortal Realms! This is a pretty fantastic army list idea. I too am hankering to try out the Steam Tank armored company
At first I was like "why so many Cogsmiths?" but duh, they can heal multiple tanks. So actually I think that's a fair idea, but they are kinda slow so most of the time you'll probably have to run them, meaning they can't shoot their guns.
Also applaudable is the use of multiple Gyrocopters. I have used 2 singles successfully in a couple games to achieve a couple battle tactics and nab unguarded objectives, and even took out some Savage Orruks in a big group. However if you have that many, I might use them in pairs, as let's say you can get them in range of a big horde unit, like 40 zombies. That's twice as many shots hitting on 2s (use the Steam Gun) with a single Command Point. Guess if you want to try the Brimstone Guns, might be a decent weak-hero sniper especially if you can drop some bombs on the them too.
For Gyrobombers, I have tried them but they move more slowly. My only idea with those would be to hide them behind a set of Steam Tanks, and move them up and back 6" (which still counts as a normal, and then you could repeatedly bomb whatever is trying to kill your tanks in melee.
One other thing I might recommend is taking a Celestial Hurricanum instead of the 2 Battlemages....and just drop one of the Gyrobombers to pay for it. Then give that the Arcane Tome, and you'll get +1 to cast on casting 2 spells. Magic is tough to get off these days, and shouldn't be relied upon, but sure is helpful when it does work! Not sure the Cogs is necessary...might try something like Soulsnare Shackles or Geminids to debuff and hinder your enemy instead. But practice will help you find your favorite tricks.
If you can take pictures of your battles and write some reports, it's always interesting to read and see what rare armies do!
Automatically Appended Next Post: Oh, and another interesting way to play Cities, and still using Steam Tanks, would be to go with Tempests Eye and coalition ally in a Kharadron Overlords Frigate or Ironclad, and maybe some Grundstok Thunderers or Arkanauts to ride in the ships. You'd probably not be able to use any Gyros then or Endless Spells for lack of points, but would change it up a bit and stay more mechanized in theme. Though I am a bit of a purist with my Cities armies lately and want to find some glory with their cool looking warmachines.
