I've always responded to d4 with the Nimzo/Bogo Indian (if Nf3). These are all solid responses employed even at the highest level. Even in the most trying situations, Black is left with only a slightly inferior position. However, sometimes, this isn't enough.
The Bogo-Indian positions are somewhat frustrating. They offer White a lasting advantage in development and tend to be ultra drawish. (think 48%!) Thus, not only does it leave Black with an inferior game, it also leaves black with few winning chances. Needless to say, I am looking for a substitute.
I've been looking at the Queen's Indian with b6 instead of Bb4. The Queen's Indian is the most common GM choice in these positions and it's well known for its solidity. However, Black scores only a little better and draws almost 46% of the time. Again, not something I look forward to.
Searching for a less drawish opening which is still solid, I've come across the offbeat Black Knight's Tango. It goes like this: 1. d4 Nf6 2. c4 Nc6!? At ~30% for draws, I'm already interested. Even more remarkable, out of ~1300 games, Black scores an excellent 51%. It's surprising it isn't played more often. Apart from Christiansen, Yermolinsky, Bologan, Epishin and Zvjaginsev, I haven't seen any strong GMs using this opening.
What do you guys think about this opening and why wouldn't it be played more often?