I suspect you won't want to be running Llanowar elves in any 3-color deck except Abzan (Junk/BWG) because that gives you 8 shocks that make green. Sultai is not gonna have the 14 turn1 untapped green sources you really need to leverage all the power from Elves.
White would give you some cool new midrange options at the (already crowded) 3cmc slot, like Knight of Autumn, plus some other removal. GB midrange looks to have many tools even without splashing, though.
I had just switched AWAY from building Sultai b/c of the lack of good 1cmc removal, and bought stuff for Grixis figuring to use Shivan Fire, but now they slip a Dead Weight reprint back into the file! I was even thinking specifically that I wished Dead Weight were still around. Oh well, suppose I'll be able to switch between the two now depending on whether Ass-Tro ends up being good or not.
$15 for a slightly-upgraded Flood of Recollection is likely to be the biggest bust of the pre-sale season. Being vaguely similar to an awesome card is a traditional recipe for this. And bear in mind that it took about 8 imitation Dark Confidants before they finally printed a playable one with Siphoner, and that card was still only worth a few dollars.
White would give you some cool new midrange options at the (already crowded) 3cmc slot, like Knight of Autumn, plus some other removal. GB midrange looks to have many tools even without splashing, though.