If you really want to fight aggro straight U/R is the most consistent. You don't play pushes, but you play the energy suite alongside 4/6 t1 removal, and play a deeper control game from there. It doesn't have any mana issues, it can afford to run on lower lands, and magma spray (omitted here for push) is quite a good card even in duels. You don't need black for this.
Grixis as presented here is basically 95% favourite vs anything even approaching midrange. That includes walker decks and most aggressive 23 landers (although hasted gruul might steal more games than you would like). It's not quite as perfect vs deeper control (many dead cards, will be reduced to jamming walker threats into counterspells) or vs hyper aggro (burn finishes you off).
I think with Chandra, Flamecaller and the upcoming Bolas, one could envision grixis being built more as a tapout control deck, with the only true weakness being enchantments (which would mean maybe trying to get a bit more incidental damage in, so 1 swing from a disciple or a resolved bolas are confirmed kills).
From this angle, I quite like Cut // Ribbons, but it's a bit fragile, since Never // Return is quite popular.
Long story short :
Dark Intimations is a SWEET card, and this deck will do fine on ladder... in the theoryscape of magic duels, I think there are too many weak points compared to esper or jeskai to play this instead.... but yeah, those decks don't get to play baby
Cruel UltimatumAlso this deck is soft to vehicles...
You really need harnessed Lightning.
6/10