Sharuum has much better colors than Teferi and the ability to win out of nowhere with combos over Derevi. Your lock might not be quite as strong but you have a much better win condition to make up for it. Also, being able to repeatedly recur stax pieces is pretty powerful.
I've been pretty active in those Stax Sharuum threads; I think there's a lot of potential there. The traditional engine build's biggest weakness IMO is that it has trouble dealing with combos that can go off before we get our engines online, and a stax shell helps alleviate that a lot.
Are you running Mind's Eye and Oracle or just Eye? It might be worth it to include both now if you're not, just for the redundancy. Also, if you're having trouble with Shroud/Hexproof players stopping the Bitter Ordeal combo that's another reason to give Altar of the Brood a shot, in addition to the reasons I posted a while ago (mainly that it's revivable via Sharuum and is tutorable via AI alongside Map>Mirrorpool so that any tutor that gets us to AI can assemble a combo with no other pieces required other than an artifact in hand and a turn for Pool to untap).
I've been trying Sorin and although I haven't gotten a ton of games in with him he's been absolutely nuts every time I drew him. I'm totally sold on him as a 1-of. That said, I wouldn't even consider dropping Vault for him.
How's the mainboard All is Dust been? I've been running a pretty similar list to you, the major differences being Dismembers over Go for the Throats, a slightly different mana base and a 25th land over the AiD. I've been thinking about dropping a land for another spell but every time I'm about to make the change I get mana screwed and reconsider.
The biggest issue I see with Citadel (aside from space) is that we generally want to run some number of Stony Silences in the board and they really don't play well together. I guess MLD is another reason to run Warping Wail though.
The problem with Leyline is that if it's not in our opener it comes online way too slowly. The problem with Rest in Peace is that it makes Lingering Souls a lot worse, which is one of the main reasons to play white in the first place. Multiples of either is also a huge dead draw, while extra relics cycle themselves.
Is there a consensus on Eye/Urborg/Map ratios? I've been using 2/2/2 with 24 lands, but I also see a lot of lists with 3/2/0 and 25 lands. Is it mostly preference or is one starting to prove itself as the better choice?
I don't think I'm changing anything mana-wise, 35 lands plus like 14 other things that make mana should be enough.
I have been thinking about running Altar of the Brood, though. Now that Mirrorpool is a thing running Altar lets Artificer's Intuition search both a clone (via Expedition Map) and a way to make the loop lethal, which I think is more relevant now that we can't partial our way to tutors/combo pieces as easily. It's also just generally easier to tutor for and recur than Ordeal is.
I think I'd rather have Matter Reshaper than Endless One. We can't play him turn 1 but he still does a good job of being an early game roadblock against aggro, and unlike Endless One he replaces himself with a card that can potentially be a free land drop or another copy of himself or strangler. Late game 3/2 is still big enough to be relevant, and by the time Endless One is getting huge we should be casting eldrazi with actual effects anyway. I'm also not a huge fan of Smasher, as other people have said he's just a beatstick. Our entire deck is beatsticks that also have immediate impact; we don't need what is really just a faster clock when we already have the Titans to close games out.
Honestly the only thing about Smasher than really excites me is that he's practically unkillable if we shred their hand down with Seer and discard spells, and at that point we're already winning anyway. (EDIT: also notable that he can come down and smack Karn for 5 the same turn, which is nice but maybe not necessary since we have more early bodies to throw at him anyway.) Also, I think Reshaper is a great card to improve our early game but I don't think I want to drop Strangler for him entirely; maybe 2-3 Stranglers and 3-4 Reshapers would work? I think my creature lineup will look something like
I think Endbringer and Kozilek are worth trying out for sure. Endbringer just does so much: pings X/1s to death, draws cards, blanks ***** like Wurmcoil/lone infect creatures/anything wearing a cranial plating if they don't have BB to move it mid-combat, attacks and blocks as if he had vigilance, etc. If he comes down early he can just take games over singlehadndedly. As for Kozi, my though process is as follows: most of the time, Ulamog will be the better choice but many of those times Kozilek will still win us the game by virtue of being a giant beatstick with menace that refills our hand and can potentially counter anything that would stop him (not always, but he does draw us a ton of cards when he lands so there a better chance of us having the right cmc in hand to stop a removal spell). The times when Kozi IS the best choice, Ulamog doesn't do *****- for example, if we're at low life vs burn or twin Ulamog can't save us from bolt-snap-bolt or just more burn to the face unless exiling 2 of their lands prevents them from being able to afford the spells entirely. So, I think that a 1/1 split is better than running 2 Ulamogs because since you can search the right Titan for the situation with Eye anyway you might as well have access to both. If you're only running 1 Titan, I think Ulamog is the better choice because he's harder to remove, has a more immediate effect on the board (even though I think Kozilek has a bigger impact overall) and also happens to give us a way to win though infinite life.
I have been thinking about running Altar of the Brood, though. Now that Mirrorpool is a thing running Altar lets Artificer's Intuition search both a clone (via Expedition Map) and a way to make the loop lethal, which I think is more relevant now that we can't partial our way to tutors/combo pieces as easily. It's also just generally easier to tutor for and recur than Ordeal is.
3x Reshaper
2x Strangler
3x Seer
4x Herder
3-4x Sower
0-1x Endbringer
1x Ulamog
0-1x Kozilek
I think Endbringer and Kozilek are worth trying out for sure. Endbringer just does so much: pings X/1s to death, draws cards, blanks ***** like Wurmcoil/lone infect creatures/anything wearing a cranial plating if they don't have BB to move it mid-combat, attacks and blocks as if he had vigilance, etc. If he comes down early he can just take games over singlehadndedly. As for Kozi, my though process is as follows: most of the time, Ulamog will be the better choice but many of those times Kozilek will still win us the game by virtue of being a giant beatstick with menace that refills our hand and can potentially counter anything that would stop him (not always, but he does draw us a ton of cards when he lands so there a better chance of us having the right cmc in hand to stop a removal spell). The times when Kozi IS the best choice, Ulamog doesn't do *****- for example, if we're at low life vs burn or twin Ulamog can't save us from bolt-snap-bolt or just more burn to the face unless exiling 2 of their lands prevents them from being able to afford the spells entirely. So, I think that a 1/1 split is better than running 2 Ulamogs because since you can search the right Titan for the situation with Eye anyway you might as well have access to both. If you're only running 1 Titan, I think Ulamog is the better choice because he's harder to remove, has a more immediate effect on the board (even though I think Kozilek has a bigger impact overall) and also happens to give us a way to win though infinite life.