That aside I wonder if you would be willing to post a sample of your Nurgle Khorne lists Mentat.
Tomorrow I am trying this at 1750.
Herald of Nurgle w/icon *
7 PB, Icon *
7 PB (herald here) *
8 BL, icon (skulltaker here)
DP, flight, MoK, blessing *
DP, flight, MoN, breath *
* = preferred wave
I have some other gifts on the GUO and DP
I'll most likely be playing a mech Blood Angel list in a Cities of Death scenario. Last week my opponent fielded Mephiston. I'm expecting multiple dreads this week including a librarian, so I hope my DPs are up to the task.
The Herald of Nurgle isn't very good, but I have the miniature and I play WYSIWYG and painted only, so some of my army selection is based on that. Actually I use him more for a WYSIWYG icon than anything else.
Skulltaker is on foot, but most of the time when we play a game with objectives he can get into the action. (I'll bring him in near the thick of the fighting). I just got the painted GUO and I haven't tried him yet. I also have not tried the Daemon Princes before so I will see how they work out.
I will generally be aggressive with the plaguebearers and get them near some enemy who are near an objective. If they survive, I will usually slaughter the enemy army with the bloodletters in the 2nd wave. It only takes a couple to make a mess of a marine squad.
My more typical Khorne/Nurgle list at 1000-1500 is something like:
Skulltaker and/or herald of Nurgle (sometimes only the herald of nurgle for a cheap HQ)
multiple squads of 7 PB
multiple squads of 8 BL
2 Soul Grinders with tongue (greatly annoying to my opponent)
I have used Flesh Hounds in the past but only because I have 16 painted
I always stack all Soul Grinders in my first wave along with PBs to plant icons and try to tie up enemy squads.
Now, before the "professional" players trash my lists and say they will never win, or that I am only playing unskilled opponents, let me say that success with daemons comes down to your ability to be flexible and make use of what you have available where and your ability to make the best of it.
I have been playing since around 1992 with various armies and I'm not going to say I am a great player but my "regular" army is pure infantry Deathwing and I win most of the time with that against a wide variety of armies (including at tournaments). I could make a NETLIST of any army I wanted, but I have a lot of fun with mono and dual god daemon lists.