Ok,
Here are the chief candidate moves for Black after 11.Nb3:
- 11...Bb4
- 11...Be7
- 11...b6
- 11...Bxe3
- 11...Something else.
11...Bb4 is the most popular move, and was played in the important game, Anand-Morozevich, San Luis 2005. Anand destroyed Moro and made the entire opening look awful. But it may not be so bad if Black can come up with improvements after 12.Rhf1! (12.Bd3 and 12.g4 have also scored well for White.)
11...Be7 has been tried several times, but it just doesn't solve any of Black's problems.
11...b6 is the most interesting of the alternatives to 11...Bb4. However, that too has not scored well for Black.
11...Bxe3 is thematically suicidal. Psakhis considers this to be just bad and spends almost no time on it. Suicidal or not though, it has had some positive results in the few games (between weaker players generally) that I've found.
Black's basic problems can be summarized simply:
A) White will get a tremendous king-side attack with some variation on a theme of Qf2-h4, R-3rd rank (hence Anand's Rhf1), sac on h7 or push f5-f6 and mate.
B) The endgames for Black are generally classically abysmal. The light squared Bishop rarely plays any part except as spectator. GM Rowson showed that the N vs B endgame in this case really is horrible for Black. That's why 11...Bxe3 is so rarely played. In most games, White simply crushes Black on the kingside while the Bishop does nothing.
The most common variation goes something like:
11.Nb3 Bb4 12.Bd3 b5 and White is already gunning for a huge kingside attack without any worries from Black's B on c8.
I'd appreciate any advice and concrete variations!