Don't forget about Fiery Impulse in UR Control. It's something we've got that standard doesn't. Joly played it in the past tournament with his Jeskai Control and made it fairly far (3rd place). Also, Kozilek's Return is a nice instant option and I always find it to be the blow out play.
_The only thing this variant is missing is artifact/enchantment removal in the form of Frag & Nahiri. Mainly there only to deal with Tutelage and not vehicles. Vehicles are just above average sized creatures.
_Anguished Unmaking is the card I feel that defines Esper. It's a nice immidiate answer to PW's but you can sort of replace that with Tower and more counters.
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gives you Fatal Push but Grasp isn't better than Harnessed because it doesn't deal with 5 toughness guys like Flagship. Languish is still a solid option, Liliana is the best walker in the game and Dark Intimation feels more like a 2HG card.
_On the last note, the 3-mana spot removal in Murder and Unlicensed is mainly only there to answer 5 toughness + guys. I find it to be too slow vs. the faster decks like vehicles.
Yeah, I think right now the biggest weakness of Grixis is lack of good enchantment/artifact removal. Things like Tutelage, Visions, and Dynavolt are the bane of the deck.
Dynavolt and Burn do a pretty good job of answering PWs, and Intimations can and does hit PWs. Grixis can run counterspells too (although they generally tend to devote less room to them than Esper).
Intimations has actually been pretty good to me, being able to freely -X your PWs (or cast them into a situation where you know they will be removed in short order) knowing we can always grab them back up later from the yard has won me a lot of games. Doing stuff like playing Ob, killing a creature, and letting the opponent kill Ob with combat damage the following turn (effectively Fogging the turn) just to follow up with Intimations to remove another creature/PW and grab Ob to slam down again the following turn.