Congrats you both on your great results with a great deck
I like the decklist and came to the same conclusions in many cases. (how do the red splash version look btw?)
Senseis Top is a good Brainstorm No. five and fits this role better than Ponder in this deck for several reasons: You use a lot of colorless mana, you have plenty of shuffle effects and you can use it as protection against too much Confidant damage. I also play Tinker/Col in the sideboard, so Top also acts as Tinker target in my list. So, when you see Top just as another Brainstorm effect, it is not random.
Dazes: I love them too and would not play less than two (I play three). Your list differs a bit, as you play one more three-mana-spelle, but the rest of your deck basically doesn't cost more than two mana, especially the broken bombs like Confidant, Mask, Stifle-Nought. Daze perfectly fills the role of protecting your bombs or to support your disruption package (playing Duress for example, holding mana open to Stifle a fetch and still be able to counter stuff). I very often just play things with nothing more than two mana on the board, so Daze is fine. I would love to run Misdirections as well, but you already get plenty of damage and I wouldn't love to flip another five-mana-spell.
Trinkets: In the full Dreadnought build I always found Trinkets just too slow.
Imperial Seal: You are probably right and I should give this a try as well. It just happened to be that I very often played Mystical during upkeep for the überbroken Time Walk. I also play Yawgmoths Will, so this would be a difficult cut. Also I don't like the life loss caused by seal, because as I already said, I want to keep the possibilities of life loss at a minimum, as there is no way I would ever cut Confidants.
Cutpurses: I have toyed around with these as well. Sometimes they were broken, but in average I would just say so so. There are so many blockers around and it got worse with Painter entering the field. Additionally it costs three mana with double color. I cut Will for a while for a Cutpurse - quasi as Confidant No. five - but meanwhile came back to Will in the maindeck. This is not Grim Long, but with Petal and co Will can still generate horrifying card advantage - even in this deck.
Thoughtseizes/Duress: I always have been an opponent of Thoughtseizes in this deck (life loss ...) but with Painter as a top deck, I changed my mind a bit. Now we have two combo decks that really got hit hard by getting a creature out of their hand. And this also fits with my sideboard plan against painter. So yes: I would add Thoughtseize as well but am just not sure about the right number. Did you like the 2/2 configuration?
Color Splash: I tried out green as well, mainly for the same reasons as you did: Predator! A very flexible critter against so many decks. But I think, it doesn't really make the cut. Against Workshops it can be very effective, WHEN it enters the field. But this can be very tough against its mana denial elements. Against Oath and Painter in my testing sesssions it very often came too late, and it also can be hit by REB. So I am not sure by the green splash anymore. Goyfs are great in an aggro field, but not more. We already do play pretty big critters
Red might be the way to go, to fight Painter. But I think you can try it out with the simple U/B shell as well. A good combination of Thoughtseizes/Extirpates/Smothers might serve as answers, as the Painter is the part the deck is mainly build around. Withoug them, its much easier to beat them, especially as they cant block Confidants anymore
