First of all, I would thank Tom and other designers and playtesters. I thank every new addition to Bloodbowl that could be tried. Even better if it is well designed enough to be officialy playable in the future. More variety is never bad.
I tried to follow the thread but maybe I missed some points. I would comment to add my opinion about the roster:

Playstyle. This is not a problem for me. I mean Khorne has its own background in Warhammer, but in the same way Slann have and don't follow the WH representation in Bloodbowl. It is better for me to have a new roster with new gaming style more than a more bashing Chaos just because it is Khorne. As said, you could use this roster as Savage Orcs, Chaos Norse, etc.
Taking this into account, I found some decisions in the teams quite particular, and I would thank any Galak/other designer comment about them. If were previously addressed, sorry, I will search for the answer. This is not merely a critic, it is just a list of questions to know the why the roster is at it is.

Pit fighter name. Was an imposition from GW to continue having miniatures in range to supply the team? Other options were available I guess.

Bloodletters without Frenzy but Heralds do have. They are quite similar positionals (could be another question: why to have this very similar positionals splitted instead of making just 0-6 khorne daemons?).

Nurgle, Chaos Pact and Chaos are allowed to take mutations, even Chaos Dwarves. It seems to be a trademark of Chaos teams. Why Pit Fighters couldn't get Mutations at least? Instead of that they pick Pass. Sounds quite strange to me. I feel this team could play in open gaps in defense pretty well, and possibly Pass are potentiating this quite, but can't figure out how yet.

Shouldn't have the Big Guy at least ST like a Treeman?
Resume: I think would be interesting to have a little about the story of this team. I would appreciate so much personally. I have no issues with the nerfing/overpower of this team. Underworld seemed a very weak team for most at the beginning and I love play them, so I would first try to play Khorne and get the profit with them (I feel they have some dirty tricks there, just need to find them). But comments on why Heralds do not have ST4, why split bloodletters in two positionals... Is the most interesting thing in the desing more than the final roster (e.g. the two rosters addressed by Galak at the beginning of the design, the Cyanide's guidelines...) if it is possible/legal to comment that. It could be played in any way.
Thanks Tom & others!