@Markovich, there is less theory, in the form of concrete variations, but much more in the form of if-then-else statements
e.g. if Rc1 and Qc7 has been played then black should always watch out for a Nd5 tactical possibility, and when I say "watch out", I mean he has to sit there and calculate Nd5 in every move.
Move-order is another issue..
e.g In the mainline - what people call English Hedgehog, black should delay 0-0, because at some point he has to play the queen outta the d-file and qc7 is the place to go. But in order to do that safely, he has to play a6 before that. And if he has chosen to castle early, the tempos aren't enough for him, so in this case he plays Qc8, then a6, then Qc7 losing a crucial tempo.. If he tries to cheat keeping queen on c8, white creates a Be3+Qf2 battery pressurizing on b6.
I am lucky to have met a strong player recently and he has shown to me numerous examples like the above. The whole system is still beyond me, but I have the ambition to study and play it in the future.
Black has great winning chances from what I've seen so far. It is very easy for white to overextend and then black plays 1-2 pawn levers and suddenly his pieces become very active.