I just finished a DA campaign. Early game felt pretty difficult, not so much because of the ships, but more because of the remote location of their stations and the necessity to cross the "ocean of hyperstorms" to reach Outer Terminus (played corvus mode). Otherwise, it was a pretty fun ride, even if i struggled quite a bit during very late game, being "forced" to use fighters with the current ship slot system.
For the ships, the Vapor frigate felt like a Wolf on steroids. Like its vanilla counterpart, it's a glass cannon that rely on mobility and with its evasive system, it's an ideal starter ship. Really hard to catch but still extremely allergic to Salamanders. The standard variant i started with felt very underwhelming, the attack variant with the dual Grave/Recson is infinitely better for pirate hunting.
The Draft is a strictly support ship, and a pretty good one as a first wingman. It works like a Kite or Vigilance, you have to escort it while it keep the pressure with its 4 small missiles. A Salamander Draft is a pretty mean ship to anything without omni-shield. The lack of shield isn't a problem for early game, even though the Arcus armor will rapidly show its limit against bigger calibers.
In the destroyer category, the Calm is just a bigger Draft. It flies like a non-crappy Buffalo MK.II. It can brawl surprisingly well (kinda) against frigates early on, thanks to the two armor drones. It's still pretty much a purely fire-support ship though.
The Hayle is like an hybrid between the mobile Medusa with the firepower of the Enforcer. I think it's the best Diable flagship for the player, it's really fast and the huge frontal missile firepower make it an amazing hunter killer. Not fantastic for the AI though, the frontal shield coupled with long profile, with the teleporter on top of it make it an easy target. It can still be built as a fire support though, but the Calm's here for that already.
Like said earlier in the thread, the Stratus is pretty much a Mule. It's not as tough, and can't mount medium missile for long range fire support, but the two Wanzers that come with it are pretty handy for early game. It won't hold it against anything bigger than a destroyer though.
The Derecho felt quite good to me. It's pretty much a Sunder, even though it doesn't quite have to same frontal firepower. The medium missile coupled with the large hybrid still make it a pretty dangerous ship, even in the hands of the AI. I'm not sure about its ship system though. I haven't really noticed any loss of tracking in any missiles, i don't know how large is the effect radius, and on top of that its cooldown is surprisingly long...
Then we got the Fractus, which is a Condor, with more guns (and drones), and that's pretty much all. I guess it can make an interesting front line ship for early game, like the Stratus. It's still pretty good to get wanzers on the field relatively early, as DA can't really fight without them.
For the cruisers, i found them to be quite expensive. The Gust is a more expensive Heron that trade its second launch bay for the built in HTPC. It's still very fragile, and the limited range on the HTPC force it to get closer to the frontline, which lower further its life expectancy. I personally traded my Gusts for bigger ships later in the game, as Diable doesn't need to resupply their wanzers as much as other factions do, and every of their capital ships also provide launch bays.
The Haze is an interesting one, but still pretty damn expensive, more than a Dominator. It's the epitome of the glass cannon, it dies incredibly easily but can dish out a lot of damage, which is interesting because DA fleets usually needs something to do the killing while the wanzers are keeping the enemy fleet busy. It's a good, if risky, flagship that allow no piloting mistakes. I'm not very comfortable putting it in the hands of the AI though, even if it can be built as a pretty good long range missile platform.
I was a bit disappointed by the capital ships, mostly expensive and not that amazing. The Storm is good because it bring a surprisingly cheap way for wanzers to stay in battle with its 4 launch bays. I found it could be built in a decent broadside ship. It's not a Conquest though, and it doesn't like staying on the frontline too long. While the Storm by itself is good, fielding more than one (or two) tends to be a waste.
Its bigger brother, the Malestorm, is more or less the same. But while the Storm is closer to the Astral, the Maelstrom is more an Odyssey-like. It may be called a battleship, but its role is definitely battlecruiser. It can't brawl with the other factions big ones, which is the role i would have liked it to fill. It's also really expensive, at 50 deployment points, you can get a Paragon to wreck some faces. The Maelstorm was my backbone ship, even though i wasn't supremely satisfied with it. It's clearly more survivable than the DA cruisers, and the single launch bay is always a bonus with so many wanzers. But alas, really expensive, hard to field.
The only proper battleship of the faction is the Pandemonium, which is even more expensive. Like most of DA ships, it's very fragile and vulnerable to flanking. But unlike its two smaller capital siblings, the Pandemonium can at least bring a pretty good amount of firepower in the battle. I feel Diable always have trouble when it comes to dealing with enemies battleships, they don't have a dedicated bomber (the closest one being the Raven) and few reliable damage dealer (the Haze is supposed to fill this role, but tends to die when facing bigger ships). The Pandy is the only alternative i see when it comes to drill a hole in a tougher target, but at a pretty extreme cost unfortunately.
For the wanzers, i'm still a bit confused about their roles, as they uses weapons that don't appear in the codex and can only be guessed from their performance in battle. The Frost seems to be the Talon-like, which is supposed to intercept missiles and fighters. The Warlust looks like a Broadsword-like, an all around fighter. The Strife is a Warthog-like (the SS+ one). The Valiant is definitely a Xyphos-like, and finally the Raven is... Erh, a mix between the Piranha and the Gladius?
Not much more to say. To be honest i haven't seen any big balance issues. They may sound a bit on the weak side in my feedback, but i also played with the ExtraSystem mod that increase the strength of the enemy ships by an uncertain amount, which may have skewed the whole thing a bit.
Still, the faction is pretty good, if quite difficult to play at some times. I'm just a bit sad that the Pandemonium and Maelstrom are that expensive to field, but it's still possible that i missed something about them that would justify that high cost.