I have experiences of this, they're more based around playing smart, even I can't do a full on Nexerelin Exigency playthrough, becuase the hulls on the ships can't take much hits because of armor being destroyed so easily.
On the plus side, the 3 most useful ships i've seen so far out of this faction are the Indra, Xyphos and Irithia.
I vanquised Teresa Terror's IBB fleet thanks to the Irithia and struck her down first, but most of my fleet perished early. Thankfully, the hull regeneration stacks very and I mean VERY favorably with the 0.5 seconds hull regen, which means if health isn't full, the Irithia repairs like crazy.
Xyphos are good for flanking and skirmishes, not pure battle, unfortunately. Treat them like a sub-par Medusa with a different shield system.
The Indra is the real star of the Exigency Corporation faction mod, however, due to it's Burst Maneuvering Jets and the Burst Repulsor.
How many times i've caught ships and harassed capitals because of the systems the Indra has on it, while having the CIGEN Repeater (should call it a Chaingun really, shoots fast enough.)
The Burst Jets it has on it allow it to get in and out of a situation, all while taking out ships without sufficient armor to hold off the assault from the CIGEN Repeater when it closes in.
The Burst Repulsor, being more effective for repelling ordnance, allows the Indra to be a last minute Aegis against ordnance from bombers, MIRV's and even Reaper Torpedo's.
Now, if you ask me, not many of the other ships are even worth mentioning remotely, aside from the Pergon and it's CIGEN Cannon, due to partially being useful because of the long-range capability of it's CIGEN Cannon.
I haven't gotten any Ahriman Association ships yet, and don't plan to.
I think the best strategy for a pure playthrough is just stack Battlecarriers. They're the only hull that seems to repair fast enough to withstand an assault for long enough that the allies can help the ships under attack.