this is why people say to not trust wiki, because is impossible to verify the source

That part is speaking about their presence in the warp... after death. The Dark Eldar are being consumed while alive. Thus, not relevant. If you find a part that speaks about non-psykers not having a big enough presence to be consumed slowly while alive, then we can consider it.

But the fact that having a higher potential to being manipulated does not make it so that anyone being manipulated is proven to have a higher potential. You're putting cause and effect on its head. That is the odd jump in logic. I don't talk about any specific weirdness in the rules of 40k. It is the base rhetoric, the fundamental "X are more likely to Y, so all Y are X" fallacy.

The Eldar weren't being consumed during their life before soul stones, either. Only the Dark Eldar start being consumed before their deaths. See for instance this short story by Graham McNeil, which are all canon: https://www.eternalcrusade.com/game/stories/306-Death-And-The-Maiden-World

‘But we are safe here?’ said Ishar. ‘That’s why we came here, to get away from the danger and the horror. You said we would be safe.’
‘Aye, child, and for a time we were,’ said her father. ‘In life she cannot claim us, but in death…’
His head bowed, memory of lost love robbing him of his words for a time.
‘When we die she takes us,’ he said. ‘When we die she devours our souls and torments us for all eternity. Death for us is no longer a release, no longer a return to the galaxy’s natural cycle of birth and rebirth, but an eternal nightmare of pain and suffering.’

In life she cannot claim us... but she totally does claim Dark Eldar in life, to such an extent that they need suffering-fuel to keep her from taking them. You can hardly call Dark Eldar "safe" either, but this guy totally says that they (pre-soul stone Eldar) are safe until death. They have fundamentally different souls. I think you'll have to concede on this point, this isn't the only part of the lore that marks their doom at the hands of Slaanesh as fundamentally different.

We can discard the psychic power - fertility link for now, as the source can apparently not be traced back.

Of course their warp presence is their soul. I'm honestly not even sure what you're bringing up anymore by now. I'm objecting to you using a quote that says craftsworld eldar souls are strong enough after death and use that as evidence that dark eldar souls are, too, simply because they both get eaten. But the Dark Eldar get eaten before death, therefore it is not strictly analogous.

Again, I agree with your conclusions, but your arguments use false equivalence constantly. I'm challenging them from perspective of a devil's advocate so you may refine them. We're just spiralling further into nonsense though, so I'll leave you to it on this issue.

Just using the same words I see appear in your posts to keep the terminology simple and even. Do you honestly want to turn this into a semantics debate? I'll clarify my meaning, and may that be the end of that.

I was talking about how higher warp presence = more interest from Chaos, and an easier time attracting negative attention to yourself. Contrast with Tau, according to Lexicanum:

"The Tau have no psykers whatsoever among their ranks, for their souls are so feeble they barely register in the Warp at all. They are largely oblivious to the malevolent forces of Chaos, who in turn take no interest in the crumbs that are Tau souls. No Tau has ever been corrupted by Chaos"

Having your soul slowly siphoned is what I called "being manipulated", acted upon by a force of chaos. Admittedly, it isn ot the right word, but I'd prefer if you took the spirit of my post rather than the letter now that I have clarified the usage.

If you agree that those with a larger warp presence are more at risk from chaos attention, then we have nothing further to discuss on this point.

In this story, the Fall was 10 years ago. The father figure explicitly says they have been safe in life during these ten years. The Dark Eldar clearly are not safe in life. Slaanesh being able to see and sense you are not the same as Slaanesh being able to slowly siphon your soul away. Now, it is completely possible that a Dark Eldar who puts on a soul stone is no longer siphoned, since he is now a ghost to Slaanesh.

This does not mean that a Crawford Eldar without a soul stone is siphoned in life as well, like the Dark Eldar.

Again, false equivalence. Two people infected with a bacterial disease can both be cured with antibiotics. This does not mean their conditions are the same. A Dark Eldar and an Eldar can both be "cured" with a soul stone. This does not mean their conditions are the same. You see A -> B and then claim B -> A, without fully grasping what the arrow represents. It cannot always be flipped without consequence, to do so in this instance is a logical fallacy.

If you want to prove their conditions are the same, you'll have to find information that illustrates that directly. You will not though, as has been explained in for instance this short story, Non-Dark Eldar simply are not claimed by Slaanesh in any part until they die. They are fundamentally different. It is just how it is.

Here's the guys who wrote the lore talking about it, for instance: https://www.youtube.com/watch?feature=player_detailpage&v=-oatGPbCSIU#t=546

Notice how much emphasis is being put on this being a "different" curse, and how it's constantly Dark Eldar, Dark Eldar, Dark Eldar. There is never any mention made about Eldar suffering from the same curse. Every source about craftworld and exodite always, always talks about "after death".

From the Dark Eldar codex:
"The Eldar civilisation was reduced to a broken diaspora, their realm destroyed by the aftershock of
Slaanesh’s birth. Yet those hidden in the webway remained all but untouched. Much of the labyrinth
dimension itself was shattered into ruin, but many of those Eldar who had built personal empires in and
around Commorragh survived the birth of Slaanesh. The echoes of the new god’s arrival had wrought
insidious changes within them, changes whose horrific nature would not be guessed until later, but the
Commorrite Eldar had escaped destruction."

The webway protected them, in a way, but instead insidious changes were wrought within them. Changes that only happened to those in the webwya, not to the craftworld or exodite. The background in this text constantly talks about "Eldar" as a whole, but here it is very specific in pointing out exactly which Eldar it is talking about. Because they were affected differently, and you can't talk about "Eldar" as a whole when discussing how Slaanesh affects them. Their curses are similar, but different.

At this point you really need Codex-level proof to win me over on this point.

The part I mainly disagree with, is that Warp Presence and Psyker ability are related concepts, but that doesn't mean that a large warp presence inherently make strong inherent psyker abilities. Take a Warboss or a Primarch, they have strong warp presences, but not many of them are talented psykers. They can be focal points for warp phenomenon, especially Orks, but that doesn't mean they'll ever have any control or talent or even ability to do even the most basic psyker ability. However, a large soul does mean you have a larger bartering position if you wish to take the "easy" route to becoming a powerful psyker.

I have seen no evidence that DE are capable of being powerful psykers, only the most basic of powers. What can a DE do, well feed off others suffering and in some extremely rare cases they can have mind talks with their partner (so if they have an uncommonly strong relationship)

Well, those aren't impressive powers, and I think minor telepethy is childsplay to a Craftworld Eldar. I think you're looking at something rare (DE developing half decent psyker abilities) and assigning it as broadly applicable, which I don't think it remotely is.

The point is more that "Psykers would be easy to eat. Dark Eldar are being eaten. Therefore, Dark Eldar must be (latent) Psykers." is a logical fallacy. Nothing more, really.

People with large warp presences having the potential to become great psykers is where Kilrane's use of the term "latent" psyker comes in, if I do not mistake him.

You realize that quote heavily implies that psykers are very rare in Commoragh and that their societies are not equal (same in this context). It seems to support this side of the debate.