heh, thats funny.
Um, one thing that struck me though. How exactly do you plan to summon those plaugebearers? Who has the icon? the lords?
Anyway, from a fluff perspective I think it's a really cool, themed list that just brings out the demonic, which is awesome. But... from a gaming perspective looking at relative list strength, it has a lot of problems.
Like you said, the plaguebearers are your only scoring units. That is not good, not good at all. Your opponent just needs to kill 6 plaguebearers in each squad and you're toast. Not hard considering their save isnt the best (even if they are tough..), and they are subject to Demonic Instability every time you would make a ld check.
You have *no* shooting power at all. Like... none. Like... I dont even see a single model with a gun anywhere in that list.
With the exception of the two HQs all of your units can only move 6" a turn, making your army terribly slow and relatively easy to avoid and shoot to death.
you can bet your balls to a barn door that every enemy missile, lascannon, starcannon, railgun, or other big nasty weapon is going to target the Statured Demon Prince immidiately, which will rob you of almost 200 points right quick, and one of your very precious demon icons, assuming thats where you have them.
Although nurglings are great at staying alive, soaking fire, and tying things up forever, they aren't especally wonderful at killing things, neither are plaugebearers. Don't get me wrong, they're okay... but they're not monsters. Your HQs are your power, the first as I already said, is going to be shot to bits, and the second although configured for massive damage, wont last very long with a 3+ save and no invulnerable, and only 2 wounds. (another problem, as you'll be lucky if your icons survive to summon all 3 squads of plaguebears to the table which are, again, your only scoring units).
You have nothing to deal with tanks, except the statured lord which, again, will get shot to bits. If a person takes even a few tanks he can just ram them in your face, tank shock your ass, and make you take D. instability tests every single movement phase, pivot on the spot, and blast you with whatever weaponry he's got on the vehicle, and be super safe and ready to pull the same manouver next turn. A dreadnaught in close combat is just going to eat those nurglings for breakfast and ruin them with instability.
So, in short: a very cool, very themed army, but strategically unplayable. Sorry.
-invidious