I've found that the War Destroyer seems to be like fighting against a Heavy Cruiser when it comes to incoming direct fire weapons. Their broadside firepower, on all ships, potential is frightening as all their direct fire weapons cover FX & RX arcs.
The Heavy Cruiser is more like fighting a Battlecruiser, the Corvette is more like fighting a Fleet Frigate and the Dreadnaught is more like fighting a Battleship.
The War Cruiser is more or less equal to a Heavy Cruiser in most of the major SFB / SFC races.
Fed ships don't fare well against them and are rapidly overwhelmed, then destroyed. Klingon ships are able to cripple the Frax ships reasonably quickly, due to good firepower. I usually swamp the Frax ship with a Drone salvo, so that they discharge their aft Phaser banks, then close in close for a passing Phaser & Disrupter shot, then make distance again.
Gorn ships just kill them without much too much bother.
They don't take internal damage very well though, so a good salvo hit is very effective up chewing up their innards, especially from a Gorn fly by Plasma shooting (my son's favourite tactic!!).
I have them with pre Y175 single Drone B rack reloads. Two reload racks after Y175.
I'm still writing SFC 1 Skirmish scripts for them, now that I've finished the models. I'll post them for download at sometime in the future.
If anyone wants them for SFC 2 I'll have to convert them from SFC 1 in my usual way.