So, having read both the article in the print edition of Star Wars Insider, and the one from the online edition, I strongly recommend the online article by Abel Peņa - he's done his usual fantastic job of reconciling disparate sources by placing them in a context where they make sense together. He's even managed to bring King Adas, from Tales of the Jedi Companion, back into the picture.
The print article by Drew Karpyshyn (who?) is not so good, however. First is my now recurrant annoyance at saying the Dark Jedi did not reach the Sith homeworld until after the Hundred Years Darkness, now placed c. 7000 BBY, despite the clear evidence in the primary source material of Kevin J. Anderson's comic Dark Lords of the Sith, which states that the Dark Jedi who were fleeing the First Great Schism reached the Sith. The version printed in the New Essential Chronology was clearly meant to retcon the version in the comic, but the language left things a little open to interpretation. This article, however, states that the Legions of Lettow were utterly wiped out by the Jedi - which of course precludes the idea that some escaped and found the Sith, who were then not discovered again until 7000 BBY.
Further, it states that Korriban was the homeworld and capital of the Sith Empire, when other sources are clear that is Ziost, while Korriban is the Sith funerary world with the tombs of ancient Sith Lords. The print article also uses Korriban as the planet where Naga Sadow fell back to, and was ambushed by Ludo Kressh. That world isn't named in the comic, but it makes no sense for it to be Korriban (nor does it look like a mountainous and volcanic world from space), when Sadow's base of operations from which he launched the attack was Khar Delba. It's like the only Sith world the writer knew about was Korriban.
Plus there's little things - like the picture of Sith weapons, that includes a discblade, which is from the Zeison Sha tradition and has nothing to do with the Sith.
The article ends with comments about how the death of Sidious and Vader not marking the end, that the Sith will return. While this is already coming true, it dates the ostensible origin of the document. It is written from the perspective of a Sith, or Sith aspirant, who lived in the Interregnum period after the death of Lord Sidious, before the rise of Lord Vectivus.
My personal guess is that it is the work of Hethrir, Vader's failed apprentice. It would explain the combination of occasional insight into more recent events, with the utter lack of understanding of historic matters. There are similar possibilities, it could be the work of Sate Pestage or another acolyte of Palpatine following the death of their master, but Hethrir seems the most likely candidate.
-Scourge
Darth Acheron
Yes, the article was fantastic - and I mean the online one - even though he accidentally puts King Adas' rule at 3000 BBY, rather then the 30 000 that I think he intended.
Drew was the one who was originally going to write the other Sith hard Cover in the Old Republic era that got cancelled.
Also, Darth Vectivus was between Bane and Sidious, not after, unless your suggesting he was Jacen, which is interesting, though as of yet unproved.
Lord Scourge
Yes, I think Vectivus is a "ghost of future past", the Sith Lord that Jacen will become. It's the best explanation of the novel, and I think it's why Allston said that you could go nuts trying to figure out the logic. I've seen that trick before, though, and I'm pretty sure it's what he's doing.
And Peņa puts King Ades' reign at 28,000 BBY - he writes that it is a full three millennia before the foundation of the Old Republic, which should be about right.
If this is an example of Karpyshyn's work, I can see why his project was cancelled - still being a firm believer in quality over quantity. It makes me question the tiny bits of new material in that article (as opposed to the fantastic amount of new information in Peņa's), like whether Palopatine is a fake identity created by Sidious, as he writes.
update: It looks like the Darth Bane novel, released the same day as the DVD of the original edition of the OT, is written by Karpyshyn. Given how many good ideas I've seen Peņa come up with regarding Bane's life, right now I'm thinking that this choice of writer was a major mistake, but we'll see this September - hopefully he does a little more fact-checking than he did for that article.
-Scourge
Darth Acheron
Is it? Oh... I thought his was the one cancelled, dang...
Oh, and is King Ades' reign 3, 000 years before the Old Republic? Good, , I thought it meant 3, 000 years before the Empire, .
, I thought it meant 3, 000 years before the Empire, 
.