I've played a couple more small events, and I still haven't dropped a match with TMWA. Here's where I'm at currently:
4 Dark Confidant
4 Ethersworn Canonist
3 Tidehollow Sculler
2 Jotun Grunt
2 Aven Mindcensor
2 Hearth Kami
1 Gorilla Shaman
4 Null Rod
4 Duress
2 Hide/Seek
3 Red Elemental Blast
1 Pyroblast
1 Swords to Plowshares
1 Path to Exile
1 Diabolic Edict
1 Demonic Tutor
1 Vampiric Tutor
4 Ruby/Pearl/Jet/Lotus
4 Wasteland
1 Strip Mine
4 Bloodstained Mire
1 Flooded Strand
1 Windswept Heath
2 Badlands
2 Scrublands
1 Plateau
1 Plains
1 Mountain
1 Swamp
SB: 3 Extirpate
SB: 1 Hide/Seek
SB: 2 Shattering Spree
SB: 3 Grim Lavamancer
SB: 2 Vexing Shusher
SB: 1 Yixlid Jailer
SB: 3 Engineered Explosives
I decided on Hearth Kami because he helps in some game 1s (Stax, Tezz, Dredge), can disrupt some sideboard targets against Fish-style decks (mostly Jitte), randomly blows up moxen against mana screwed opponents, and, most importantly, attacks for 2.
I'm still not sold on the Shushers in the sideboard. Nobody plays Shaymora at our small events, so I haven't found out if he's good there or not, but he's nice because sometimes you've got 8 dead cards (the Null Rods and Red Blasts) and you just need to bring in a guy who attacks. For now, I'll keep them in, but they could easily become extra Jailers if more than 1 person plays dredge at our tourneys.
I'd like to possibly find room for the 4th Sculler, but the only cut that's making sense to me is the Gorilla Shaman (who I've activated all of twice so far). Opinions?