I believe you, but can you point me to the source? (I am assuming a Brandon Sanderson interview or blog post)
Brandon has confirmed that there is a Duladel in WoK in an interview. Most of the other things we know about these folks are based off of logical inferences from the text of the book itself. The main connection is that those three people are (a) looking for Hoid, (b) look nothing like any of the "standard" races on Roshar (c) use a Duladel word from Elantris and (d) Hoid claims that the 17th shard is trying to find him, but he has mislead them. These facts make it likely that the Purelake searchers are planethoppers from the 17th shard looking for Hoid. We've had long discussions along these lines, and most people seem to agree with these conclusions.
12 - Old Friend, I hope this missive finds you well. Though, as you are now essentially immortal, I would guess that wellness on your part is something of a given.
13 - I realize that you are probably still angry. That is pleasant to know. Much as your perpetual health, I have come to rely upon your dissatisfaction with me. It is one of the cosmere's great constants, I should think.
14 - let me first assure you that the element is quite safe. I have found a good home for it. I protect its safety like I protect my own skin, you might say.
15 - You do not agree with my quest. I understand that, so much as it is possible to understand someone with whom I disagree so completley.
16 - Seven and a half years ago
17 - Might I be quite frank? Before, you asked why I was so concerned. It is for the following reason:
18 - Ati was once a kind and generous man, and you saw what became of him. Rayse, on the other hand, was among the most loathsome, crafty, and dangerous individuals I have ever met.
19 - He holds the most frightening and terrible of all of the shards. Ponder on that for a time, you old reptile, and tell me if your insistence on nonintervention holds firm. Because I assure you, Rayse will not be similarly inhibited.
20 - Seven years ago
21 - One need only look at the aftermath of his brief visit to Sel to see proof of what I say.
22 - In case you have turned a blind eye to that disaster, know that Aona and Skai are both dead, and that which they held has been splintered. Presumably to prevent anyone from rising up to challenge Rayse.
23 - You have accused me of arrogance in my quest. You have accused me of perpetuating my grudge against Rayse and Bavadin. Both accusations are true.
24 - Neither point makes the things I have written to you here untrue.
25 - Seven years ago
26 - I am being chased. Your friends of the Seventeenth Shard, I suspect. I believe they're still lost, following a false trail I left for them. They'll be happier that way. I doubt they have any inkling of what to do with me should they actually catch me.
27 - If anything I have said makes a glimmer of sense to you, I trust that you'll call them off. Or maybe you could astound me and ask them to do something productive for once.
28 - For I have never been dedicated to a more important purpose, and the very pillars of the sky will shake with the results of our war here. I ask you again. Support me. Do not stand aside and let disaster consume more lives. I've never begged you for something before, old friend.
I do so now.
I find the assumption that the above Epigraphs are all part of a single letter written by Hoid to be a completely reasonable and highly likely theory (excepting the ones that give a time frame (X years ago)).
Taking that to be true and further presuming that Rayse holds Odium (hatred) the question becomes who is Hoid writing this letter to?
Chapter 18 tells us it isn't Ruin or Hatred (Ati or Rayse)
Chapter 22 tells us it isn't Aona or Skai (two Shardholders from Sel)
Chapter 23 tells us it isn't Bavadin
Chapter 27 tells us whoever it is has some control over the group known as the 17th shard (possibly Blunt, Grump, and Thinker)
My problem is that between Chapter 22, 26 and 27 I don't see how the 17th shard could be based on Sel (though I guess it could be pulling members from multiple worlds given that it is by definition a multi-world organization).
Cultivation seems the most likely addressee of the letter (it needs to be a shardholder (not to be confused with shardbearer) who is actively passive with respect to Odium, which implies one who calls Roshar home), though Honor (also known as "The Almighty") is also possible, though his sever case of death would seem to indicate someone else.
edit: used
[/q] instead of
[/quote] on accident