I've just read the THotD's synopsis, and my conclusion is very simple: Acheronians WERE NOT Hyborians. Robert E. Howard, in one People of the Black Circle's synopsis, for example, said Kerim Shah and Conan fought for Yasmina and the Cimmerian won. But in the defitive version - the tale - the Turanian was hideously killed by the Master of Yimsha.
In the Red Nails's draft, Valeria uses a golden band in her hair, but in the tale that band is crimson (the only two things I believe to be Howard's really opinion in that story are the burn of Valadelad and the history, told by Valeria to Conan, about Red Ortho had killed the former commander of the ship Valeria left - about these two points, REH did an omission, not a contradition when he rewrote Red Nails).
Hey Fernando! First off, I just want to say that I welcome anyone who is deeply interested in the "history" that REH so carefully constructed for his yarns. You mention "contradiction" and "omission". Why is the fact that REH doesn't come right out and say, "Xaltotun was an Hyborian" in the final draft a "contradiction" and NOT an "omission"? I believe that Taranaich and I have demonstrated that Howard subtly indicated Xaltotun's "Hyborian-ness" (see posts #1 & 5).
I could give you several examples like that ones above - the relationship draft/synopsis vs. tale -, but I believe that REH's tales are the defitive version of his conception about places, characters, people... However, somethings he wrote in the drafts and/or synopsis are, in my opinion, worth to be included in the tale's plot - when the tale omits them without contradict them.
I couldn't have put it better myself, Fernando. Your English is quite good, BTW.

I also believe that any final draft takes precedence over any contradiction in a synopsis or early draft. I also believe that details that DON'T contradict the final draft are valid. "Valadelad" is one example. "Hyborian Acheron" is another.
In The Hour of the Dragon Howard changed his mind when changed the synopis into tale. So, I still believe that Acheronians = Giant Kings. Though I don't agree with Rippke's timeline in some points, I think he's sure about others, like Acheron's origins...
If you don't mind my asking, Fernando, how do you know that "Howard changed his mind" when he turned his "Dragon" synopsis into the first draft (which we haven't seen) and on into the final draft? We do have his "Notes" for the novel. Nothing about "giant/monster kings" there. As I've noted (see Post #27), it seems very strange that REH should suddenly, completely "shift gears" and toss in this "g-k" stuff without a whisper of it anywhere, especially since the "giant/monster kings" seem to be "Sons of Set" (ie, giant, human-headed serpents). Without solid contradiction, of which there is not one iota, I am compelled to go with what REH stated in his synopsis for "THotD".
as well as Nordheimrs' one (the The Hyboryan Age essay and the tale Valley of the Worm confirm together that Snow Ape Men were, in Howard's conception, the Norsemen's ancestors).
I was totally unaware that anyone disputed the "Nordheimr came from snow-apes" paradigm.
Other important point is the Xaltotun's appearence. Is is white, but not grey-eyed neither tawny-haired like many of Hyborians that lived 3,000 years before Conan. His features (height, color of hair and eyes, and the eyes' shine) are very similar to Akivasha (doubtless a Stygian noble and, in my point of view, a giant-king's daughter), Thalis from Xuthal of the Dusk (another Stygian noble) and Thuron's ones - this last one, from the Kull's tale The Altar and the Scorpion, belongs, in my opinion, to giant king's ancestors.
Fernando, I am NOT trying to be rude, but I have to ask... You've stated that you've read the synopsis, but have you read all of the preceding posts? Neither I nor Robert E. Howard EVER tried to say that the Acheronians were "pureblooded Hyborians". According to Howard, NONE of the "Hyborian" nations of Conan's time were "pure", yet, they were STILL "Hyborian". So, holding the Acheronians to the "blonde/grey-eyed" standard is going far beyond what REH himself did. Actually, Xaltotun doesn't sound THAT much different, physically, than Trocero.

Or Tarascus. Or Brodir the Black in
The Grey God Passes. Did Brodir bear g-k blood? Actually, my ancestor in the Civil War (of Irish/English/Scottish/Tsalagi/Melungeon extraction) was 6', strongly-built, pale, black-haired, and dark-eyed. Maybe
I have "g-k" blood.

As I've noted more than once:
Robert E. Howard's description of Xaltotun remained the same from synopsis to final draft. In the synopsis
Xaltotun was "an Hyborian". If REH's initial description of Xaltotun was "Hyborian", how does the
same description become a "non-Hyborian contradiction" by the final draft? We aren't dealing with a "
Hyborian Age essay" timeline situation in "Dragon". REH began changing all of that in
The Scarlet Citadel.The Hyborian migrations took "ages" (just like the Indo-European ones). When Acheron began its imperial march, there was already an "Elder" Koth, an Elder Corinthia and an Elder Ophir; all were Hyborian kingdoms. Hyperborea had very likely switched landlords. In fact, some of the "cadre" that established Acheron may have been Hyperborean expatriates, versed in "civilization", slavery, and sorcery(?). The dark hair/eye "taint" could have come from multiple directions (as could the "sorcerous blood").
A few more observations (it's late

)... Concerning the "eye-shine" of Xaltotun and Akivasha: one was a sorcerer and the other was a vampire. Analogous, non-"giant-king" examples can be found within Howard's body of work.
The "prehistoric" Stygians of "QotBC" appear to be at a very primitive level of Copper/Bronze Age technology (CoC,p.139). Yet we are supposed to believe that these same "prehistoric Stygians" overwhelmed god-like "giant/monster kings". THEN, those same g-k's, after defeat by the raggedy-a$$ "Khemites"/proto-Stygians, packed up and sailed for pleasant Hyborian lands (why they had a navy, I don't know). Here we run into a "post-'THA'/Acheron" conundrum. Since Acheron throws the entire
THA essay (timeline-wise) out of whack, when might this "giant/monster-king exodus" occur? It might be when the Cimmerians and Picts were at their pre-Hyborian height OR when the Hyborians were just showing up. Either way, the g-k's (already decimated by the "Khemites") are able to accomplish a
naval invasion against born-again-hard barbarians defending their home territory. Let us remember that these self-same "giant-kings" couldn't hold off ragged, dusky "Khemites" when they (the "giant-kings") had the freakin'
Styx for a
moat.

Is there ONE SINGLE STYGIAN MALE THAT IS WHITE-SKINNED? Thugra Khotan? Thutothmes? Thutmekri?
There are THREE "pedigreed" members of the "Elder Race" (as I recall) in the works of Robert E. Howard: Tuzun Thune, an unnamed girl and Karon, the ferryman on the River Stagus. As Axerules has pointed out, the first two sure don't sound like what has been mooted about as the "archetype" of an "Elder Racian"/giant-king. It might also be pointed out that all three have speaking parts, yet none boast of their illustrious, powerful, semi-divine kin to the South (who never lifted an oh-so-white finger to aid their oppressed brethren).
I asked Mr. Rippke about Guron/Thuron on the "Map of Kull's World" thread (Post #26). I haven't heard back.