You've TRed twice and you think you're on your "final character build" already?
Evasion isn't going to do you any good if your Reflex saves aren't high enough. Wizards and other INT toons can take Insightful Reflexes; paladins get Divine Grace; DEX-based toons like rogues, archers, etc. are fine, of course. Sorcerers OTOH start with low Reflex saves and don't get anything to help out. You say you're going for "high DEX" but how much are you really going to invest in a tertiary stat (I presume this is a pure caster not an Eldritch Knight)? It's why it's usually easier to slap on medium armor, invest in ASF reduction, and build for MRR instead with the added benefit of better protection against spells which can't be Evaded.
But if you're going to do it anyway, make sure to grab what Reflex boosts you can. Shadowdancer has Stealthy and Lithe (+9 Reflex total); Shiradi has Good Luck (bonus is doubled to +6 if you have Luck of Heroes feat); Draconic Incarnation has Draconic Perception (+6 Reflex). I think that's the best of the "low-hanging" ED bonuses; Primal Avatar's is only +3 Reflex and you're only allowed 3 ED trees.
Otherwise, a Feydark sorcerer is pretty straight-forward: max CHA, usual caster feats, AP split is something like 41 Water Savant / 31 Feydark. The main drawback is your sorcerer DPS is mostly based on Evocation spells while Feydark SLAs use Illusion DCs. EDIT: this build is like the best-case version of what you're aiming for.