I almost played every map of yours on the Loathsome's EXU2 Coop server. Probably the closest thing to the SP experience. I have written here some opinions on how they play and how much difficult they are.
Just to let you know, monsters drop shittons of random Flares and weapons like Juggernaut HellGun and the LargeMarge, potentially killing the difficulty of the maps but still making them utterly chaotic.
Last note: my ping is really high in the server, the lag usually screws me up unfortunately.
[1]DamnationThis one is apparently kinda hard because the PiddleDoper is weak and DemonSkaarj are like everywhere. It's short anyway. Hardest part is the last section with all of those Security Brutes - which is all about throwing Flares in the right spots. A Bouncilaser Flare can take down about everything until the laser beams encounter a solid surface that they can't pass through. A DemonBlast Flare can probably kill all non-Demon opposition in the whole map.
[2]Infernal FallsGood lord that big Pizza Bag almost never dies! I was lucky anyway because a Hyper Flakker was dropped and I used it all against that thing. For the rest: the beginning is rough if you have bad ping, but you can just spam the ShitGun until the way is clear. Since the map is set outside, and monsters are placed in groups found far away from each other, Flares and Barrels don't do much wonders. InfernalFalls is not hard at all, however it's long and stamina-draining so you'll probably die several times, especially against those FuckOff Mercenaries and the myriads of Coop-only enemies.
[3]Shit StormThis map is all about securing the front gate, which is a really tough thing to do - one of the hardest things of Batshit Insane. UNLESS you manage to get a LargeMarge but it never happened here. The map gets progressively easier once you deal with the Missile Brutes and Demon Pupae, you don't even need to use Flares. One of those SkyRocket Tentacles visually looked totally fucking strange (it was like a triangle blob... with a mouth) and was unkillable.
[4]The Soul StorageI decided to use PlasmaSprayer Flares for the storage and almost killed everyone in there, except few Gasbags and Pupae, and a Super Charger that I couldn't kill in any way (kept dying by trying to kill him with the Extractor). Outside it's pretty chaotic, you get hit left and right but the enemies end up kill themselves. Died several times due to the Demon Commandos, sneaky Flak Tentacles. Flares are hard to properly use too. The level quickly ends anyway.
[5]Cursed PassageStarted easily, then I made a mistake by throwing a Bouncilaser Flares which owned pretty much everyone
Remaining enemies were history shortly after. This was always one of the easiest maps though, anybody with 0 skills online can get good results by throwing random average/high tier Flares randomly.
[6]The GauntletLag determines the experience. The first wave I died almost always because I was spawned over the big torch, surrounded by lag-invisible enemies and I couldn't do much; so I went away. However another person came in (with a way lower ping) and managed to beat the map. Another time I played this level I was with somebody else, and it was much MUCH easier, hell you could just throw Nuclear Flares and Hyper Grenades from a safe spot and call it a day. Great level though.
[7]Frostclaw Part 1As easy as in SP. I'm pretty sure a Demonblast Flare can outright kill everybody.
[8]Frostclaw Part 2Don't use Demonblast Flares unless you want to kill everyone easily. That's the first and only rule. For heavy ping users, Ice orbs are hard to avoid and the Ice Pupae are painful because you still don't have the Hell Gun (random Juggernaut cannons don't help) and you can only kill them with the ShitGun. There are many Flares to get and you can use them to make a short work of the Ice people. Died many times, but still perfectly able to get to the ending
[9]Bitter BridgeNot sure about this... the shield blocking the exit is already gone and you can end the map quickly. Was it too in SP? Even if I activate the big ambush, I don't think it will pose problems, I always found this map the easiest in BI aside Map 13-14.
[10]The Doom HouseNot that hard. People enjoy using Bouncilaser Flares that slaughter about anyone, but one is never enough. It is tough like Frostclaw Outpost, except the selection of enemies is different and what else. Shoot, die, shoot, die, throw loads of Flares. Room done. You just need to know what kind of monsters are placed inside the areas.
[11]CorruptionUnfortunately this is the only map I never played on Coop. It's probably the same sort of thing as DoomHouse until you arrive in the dry valley. Anybody can take on the Archdemon after a few tries.
[12]Doom ArenaFun, easy, chaotic and straightforward. There isn't a section that really stands out there except the LavaTitan X Demon Skaarj Lord battle at the end. Invisible-Lag bug was there so I decided to spam Contact Beam secondary against the bosses until they were all dead
First part should be pretty long though with all of those Gasbags who spawn big Pupae.
[13]DarknessThe easiest map. Of course if you die you'll lose the Searchlight forever, however you can simply spam Hellblasts/CB blasts against everybody and not even get hit. Or use Demonblast Flares and everyone pre-placed should be already dead.
[14]BlacknessSame as Darkness, except if you have tons of Flares and fuck up at the ending... strange stuff happens with Flares exploding on the final checkpoint, killing you the nanosecond you respawn.
[15]Highlands of DespairDEAR GOD.
Didn't go through this, only part of the beginning and the whole ending section. The rest was all done by another player in two hours or something. Others were all angry at those invincible orbs and were trying to destroy them. Flares are pretty much useless here, however there are chances that the LargeMarge will appear. If you have the LargeMarge, you can surely turn this map into a cakewalk, however there will be always somebody who will kill you. Always. Killing Archdemons with CB+PentaPower is still easy. The map was finished anyway, it's not impossible. Just hard and time-consuming. Everybody needed a break after this as they had enough of all the meteors and pentagram shots.
At least the LargeMarge really helps here, while in G59 Map 4 the Warlords will kill you before you can start decimating everybody with it (hilariously, the LargeMarge only popped up in BI15 and G59-04).
So? Coop works. Really, really well. However the DemonBlast Flares (is the random Flare drop caused by the EXU2Coop gametype or is it server related anyway??!?) do actually kill the fun because they can destroy enemies behind walls.
Man, I just wish some day I could play some EXU2Coop with you Waff :> Now though I have to deal with my own stuff!