I'm not a big fan of cowboys, guns and train robberies in my high fantasy game. But the cards in OTJ are very interesting designs and plenty of them could fit into a peasant cube.

Highway Robbery fixes the problem all Tormenting Voice effects have: in the early-game it's too easy to shoot yourself in the foot discarding the wrong card, but in the late-game it's a bad draw when you have no cards in hand.
This new robbery can be plotted to be cast immediately after Guttersnipe and in a pinch can let you keep a key card by sacrificing a land instead.

Reckless Lackey wears equipment really well and can turn a bad trade into a card and a treasure.
I don't want aggro decks to have access to too much first strike, so Aether Chaser is an easy swap even if the token generator will be missed.

Irascible Wolverine is glue: regardless of the archetype every red deck will need some 3-drops. And Irascible Wolverine is good value for the mana you put into it.
Breakneck Rider has been on the chopping block for a while, its effect is widely playable in theory but hasn't enough synergies to be actually put in the main deck (the cost doesn't help).

Plundering Barbarian gains tempo in any strategy as a treasure maker, also I'm still looking for ways to give my players access to maindeck artifact hate.
Spellgorger Weird has been hindered by being 3 mana value and having to be in play before casting your spells. When you're on the backfoot it rots in your hand, rarely finding a window to play it on the same turn you cast interaction.

Johann, Apprentice Sorcerer is my newest trial in the experimental slot of the Izzet section. His high toughness should keep him alive long enough to get some value from the top of the deck.
Improbable Alliance was so much worse than all other blue, red and blue-red picks. The cube has too few cantrips for it. At most it made 2 faeries over multiple turns ...but it required giving up even more tempo to play other cards that do not impact the board.

I want to try again Edge of Autumn as a ramp spell that's not useless when drawn on turn 6 or later.
Harrow hasn't proven itself better than another Rampant Growth because the lands entering the battlefield untapped didn't matter. Rarely the decks that turn cards into extra lands are also itching to trade counterspells with opposing threats on turn three. They usually try to go bigger than that.
In this slot I'm also considering Entish Restoration and Search for Tomorrow.