Thanks for all of the help thus far. I've made a few changes based on the feedback. They are summarized below.
Mainboard
+2 Hero's Downfall, -2 Doom Blade
+2 Read the Bones, -1 Omenspeaker, -1 Essence Scatter
Sideboard
+2 Doom Blade, -2 Hero's Downfall
+3 Jace, Architect of Thought
The Hero's Downfall/Doom Blade bit was simply a mainboard/sideboard trade. The deck retains access to four of each card. Read the Bones was/is tough. I don't really want to drop to playing only one of any given card. So, that really only left Dissolve, Essence Scatter, Far // Away, and Omenspeaker as trim options. Of those options, Omenspeaker and Essence Scatter seemed the best places to trim for room to include Read the Bones. Though, the early body can help against aggro. So, I don't know. Finally, Jace AoT was added to sideboard rather than mainboard because I really like Ashiok so far, and he can't coexist with Jace MA. Both Jaces can draw cards, but only Jace MA furthers one of this deck's win conditions. Jace AoT dampens aggro, so he seems a good sideboard there. His card drawing could be a boon in the control mirror as well. So, he'd probably come in there too.
Edit 1: For what it's worth, I'm not particularly attached to Dimir Charm. It's okay but underwhelming in my book. Considering cutting the Dimir Charms for one more Read the Bones and a fourth Omenspeaker.