Bumping this thread from its long, Squat-like demise to post up a beta test version of the Firestorm over Kadaku mod from MirageKnight, the guy behind the various Firestorm over <X> mods for Dawn of War, for anyone interested in giving feedback.
Notable changes:
Weapon and armor balance based on a mix of codex and lore. Bolters are lovely weapons against chaff, the heavy bolter is useful at anti-everything like you'd expect a heavy bolter to be, and Rubrics will absolutely fuck your shit up if you give them half a chance thanks to their Inferno rounds. Better bring meltas and plasmas on Chaos missions unless you enjoy the sound of bolt rounds bouncing off power armor and invulnerable saves. Thankfully bolt pistols are effective against their mortal troopers.
Altered class loadouts: Generally more versatility to go with the weapons balance. Heavies get combat knives so they aren't useless in melee anymore, bolt and plasma pistols are usable by everyone so you always have a viable backup choice no matter your primary weapon, and the standard Tactical whatever dude gets power weapons, making him the perfect jack-of-all-trades with a potential loadout for every single combat scenario, just as the Founding Primarch intended. The other classes get shit but I don't fucking play them, hence you guys getting tagged in as testers.
SM1-style health regen: You get hurt, a finisher will get you back in the fight with health and armor restore. Stims are no longer 100% mandatory.
Changes also apply to campaign, not just co-op, so feel free to run around ripping and tearing with Titus as he once did.
EDIT: New version already, MK works fast when he puts his mind to it. You'll need to open up the .zip file, go past the mod folder, and then drop the local folder in your game's client_pc/root folder. If you've got anything in your local folder already, clean it out beforehand.