Mana consistency is one of the most important aspects of deck construction to me, I don't think the deck is playable. The list looks great, don't get me wrong, but only if you can cast your spells. If we had shocklands then three-color aggro decks like this would certainly be a lot more viable, but I'm not sure enabling aggro decks to play more colors would be good for the metagame.
Sub-Optimal? Certainly!
Unplayable? Hardly.
I went 5:3 using this list just last night.
Being able to cast our spells isn't nearly as difficult as you may expect. Considering that the vast majority of the deck costs so little. Outside of a few rare draws (Brimaz/Agent/Banisher Priest) you can often get by using just a single one of each color source.
Rakdos Gate + Boros Gate, or Rakdos Gate + Orzhov Gate, or Boros Gate + Orzhov Gate is often enough to allow you to play whatever you have in your hand at the time outside of maybe the
and
cards, which are low enough in numbers to not be TOO clunky.
The only real issue the mana causes is that it often slows down your T1/T2, which is usually a big issue for aggro decks. That said, the deck has a good amount of ways to push damage through, so stalling out a little on T1/T2 isn't a complete death sentence. The deck has access to a decent amount of Evasion (Nimbus Wings, Gods Willing, Deviant Glee, and to a certain extent Coordinated Assault). It has Shocks, Banisher Priest, and Agent of Fates Heroic triggers to clear the way to push damage through. It also has Shock and Tormented Hero Heroic triggers to help push damage through.
These things make stalling out a little early on a bit less of a concern. Those first few turns aren't quite as integral here when the deck still retains the ability to close out games once the game has gone on for awhile and the board has been clogged up.
The difference between dropping Satyr or Tormented Hero on T1 and dropping it on T2 is admittedly significant. That said, I have still been able to win games (some of which were quite one-sided) spending my first 3 turns playing tap-lands. The cheap cost of the majority of the deck helps to make this possible. Have to play a tap-land on T2 isn't so bad when you can often do so and still play a threat that turn. Playing a tap-land on 3 isn't quite as bad when you can still often cast just about any combination of 2 threats/tricks/auras/shocks that turn.
Aggressive mulligans also help to make a huge difference. The deck can go all the way off of just 2 lands with relative ease, so not being afraid to risk taking 1 land hands can make a huge difference. True, there are times where you have to put yourself down a card or two to make sure you have the colors you need for the cards in your hand (like a hand with 2x Tormented Hero, 2x Deviant Glee, and no
sources), but these sorts of hands seem to occur less often than even I initially expected, especially since most of the deck only needs a single source of that color to cast. Making it a little easier on the conscious to take mulligans that contain a card or two you cant cast right away, since you know all you have to do to cast it is draw into a single source of that color.
A hand of 1 tap-land, 1 threat, 1 Gods Willing, and 2 Heroic enablers is often enough to get there by itself against a lot of decks as sad as it sounds. The scary thing is that a lot of times it isn't even necessary for the second land you draw to come in untapped, or even hit your 3rd color for something like this to go all the way.
I wont sit here and try and argue that the deck is Tier 1 or anything, because that is just silly.
I will say though that is certainly IS a playable list even with the mana issues. I will also venture to say that the deck has a higher ceiling in terms of power level than any of the 2 color Heroic lists and is only really hampered by the fact we just don't have the mana to make it so.
Or to be more concise.
2 color Heroic decks are currently better than Mardu Heroic, but only because Mardu Heroic doesn't have the mana to make the deck function like it really SHOULD.