Initially I thought I would cut the 2 Logic knots and 2 Spirebluff for 4 Opt (you'd then play 1 Hallowed Fountain and 3 Steam Vents). Then I figured I would cut 2 Serum for the 2 Logic knots back. You can also go 3-3 with Opt/Serum. Ultimately it comes down to what YOU like. But I think it's correct to cut some number of Lands/Serum Visions for at least 3 Opt, if not 4
In my opinion, after extensive testing with different lists, Geist is the way to go. Jeskai does a fantastic job of clearing the way for him to attack safely. He is also hard to remove and really only dies to Liliana or a Wrath once on the battlefield. Geist puts a clock on our opponent that lists without him can't. Sometimes even just one or two successful attacks with Geist is enough to finish our opponents out with burn.
I feel like our sheer amount of targeted removal gives us the advantage against those types of "go wide" decks anyway. Not to mention sideboard Stony Silence for Affinity as well. The main reason I'm intrigued by Dusk//Dawn is the fact that it doesn't kill a single one of our own creatures (I'm on 4 Snap, 4 Queller and 2 Geist). It feels bad when you have to cast Supreme Verdict when you control Geist and/or Queller. What I can imagine would feel good, however, is casting Dusk against your Eldrazi opponent to kill a Thought-Knot and a Reality Smasher and then swinging in with the Geist you cast in a previous turn (and even your Quellers or Snapcasters). I know Grixis Shadow has Stubborn Denials in their deck but if they don't have one in their hand with mana open, Dusk seems great. For now I'm testing 2 Dusk//Dawn in the sideboard where most lists are playing Supreme Verdict and Anger.
Is Supreme Verdict really better than Dusk//Dawn? Dusk is obviously better in the sense that it won't kill Geist, Queller or Snapcaster. But is the fact that Supreme Verdict can't be countered too relevant against Stubborn Denials or Spell Pierces?
Jeskai decks are admittedly a difficult matchup largely due to the sheer number of removal spells they pack. Beating them requires an early Etched Champion most of the time, preferably backed by Arcbound Ravager or Cranial Plating to close the game out before they can cast Supreme Verdict. Again this is tough because they will most likely counter Cranial Plating or kill Arcbound before you can place a bunch of counters on Champion.
-10 Creatures
2 Geist
4 Snap
4 Queller
-26 Spells
4 Cryptic Command
4 Electrolyze
4 Lightning Bolt
4 Lightning Helix
4 Opt
4 Path to Exile
4 Serum Visions
-22 Lands
4 Celestial Colonnade
4 Flooded Strand
4 Scalding Tarn
1 Hallowed Fountain
1 Sacred Foundry
3 Steam vents
3 Island
1 Mountain
1 Plains
Etched Champion
Aether Grid (if they pack Stony)
Grafdiggers Cage
Relic of Progenitus
Rest In Peace (nowadays lots of Jeskai decks play 4 Logic Knot and 4 Snapcaster)
Spell Pierce
Thoughtseize (can pluck Wraths or Cryptic Command or Nahiri)