Avangions need to go, I'll agree, though the para-elemental material i think may be useful if only to add more options for element adherents.If we reset to the original boxed set I personally hope that a 4e Dark Sun take avangions out and shoots them and buries them in a well, Dark Sun doesn't need fooffy angels.
DB and tieflings should be able to fit in DS with some different fluff. But they NEED TO CHANGE THE FLUFF. Tieflings can't be beholden to the Nine Hells. Dragonborn can't be...y'know...dragons. They should almost be given different names, just to reinforce that there is this disconnect (and perhaps show an example of the "reskinning" that most DMs of DS will have to do with the standard D&D fare at one point or another).
To me Darksun seems like a big departure from 4E design. 4E doesn't want you to bother worrying about how many arrows you have left, yet Dark Sun wants you to worry about even more basic resouce tracking like how much water you have.
It can probably be done but if the empahsis on the harshness of the world and difficulty of simply surviving is lost will it still really be Dark Sun?
Think of the awe/fear-inspiring sight of a cold-breathing Dragonborn on Athas.
Re-set to original boxed set and go to town.
Give Preservers a bump somewhere to make them on pseudo-par with Defilers. Maybe an extra feat, skill or Charisma bump to off-set the minus from being a Preserver. Defilers would generally be more powerful in straight combat, but Preservers have learned other things from their enlightened outlook.
Maybe run Dragonborn a bit like the Draconians in Dragonlance: Some weirdo-magico offspring twisting by the Dragon King or some such. Do away with Muls if needed, Dragonborn can take their place. Especially as Gladiators. Think of the awe/fear-inspiring sight of a cold-breathing Dragonborn on Athas.
Except thri-kreen!Now you have all the basic Dark Sun races covered.![]()

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.