I don't have NIC 72 with me right now (currently away from home).. when last looked at the article, and analysed  4. Qc2 0-0 5. e4 a year ago, i found the critical line to be the narrow 5. e4 d5 6. e5 Ne4 7. a3 Bxc3+ 8. bxc3 c5 9. Bd3 cxd4 10. cxd4 Qa5+ 11. Kf1 Nc6 12. Ne2 f6 13. Bxe4 dxe4 14. exf6 Qf5! (an improvement suggested by V.Golod in CBM and other places). 

Later this was tested in T. Woodward-J. Rowson BCh.2005 (annotated in one of Rowson's columns in NIC):   

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 O-O 5. e4 d5 6. e5 Ne4 7. a3 Bxc3+ 8.
bxc3 c5 9. Bd3 cxd4 10. cxd4 Qa5+ 11. Kf1 Nc6 12. Ne2 f6 13. Bxe4 dxe4 14.
exf6 Qf5 15. Be3 Qxf6 16. Rd1 e5 17. d5 Ne7 18. Ng3 Nf5 19. Nxf5 Bxf5 20.
h4 b6 21. Qb3 h6 22. h5 Rac8 23. Rc1 Rf7 24. Qd1 Rfc7 25. g4 Bd7 26. c5
bxc5 27. Rh3 Qa6+ 28. Kg1 Qd3 29. Qe1 Bxg4 30. Rg3 Bxh5 31. Bxh6 Bf3 32.
Qa5 Kh7 33. Be3 Qxd5 34. Qa6 Qc6 35. Qc4 Rd7 36. Rh3+ Kg6 37. Kh2 Qd5 38.
Rg1+ Kf7 39. Qf1 Qd3 40. Rxg7+ Kxg7 41. Qg1+ Kf8 42. Rh8+ Ke7 43. Rxc8 Qd6
44. Qg7+ Ke6 45. Qg8+ Kf6 46. Rf8+ Qxf8 47. Qxf8+ Rf7 48. Qh6+ Kf5 49. Qg5+
Ke6 50. Qg6+ Rf6 51. Qe8+ Kf5 52. Qd7+ Kg6 53. Bxc5 1-0

despite the result, black was okay in the opening.

Also not sure what to make of Vallejo-Leko Linares 06, where Black played supposedly less critical continuation 9... Qa5!? 10. Ne2 cxd4 11. cxd5 exd5 12. f3 Nxc3 13. Nxd4 Ne4+!? (another CBM suggestion, improving on Hillarp Persson-De Firmian which went 13... Nb5), and Black went on to win. 

is 4. Qc2 0-0 a draw now? Does anyone know a good, aggressive setup for White?

Looking at recent games Dreev-Ponomariov Poikovsky06, and even Leko's two losses recently against Topalov and Van Wely at Linares and Corus this year, were not so inspiring for White. Vallejo has been experimenting with 5. e4, but its becoming exhausted.. 

@Kylemaster: 

Thanks for that information. After 15.-,Qe6 the 16.cxb6 trick is still possible but here Black seems to be ok.

I have been looking at 4.-,d5 recently but not yet tried it out OTB. I think I have found a flaw in the existing theory (or maybe I don't own the right opening books and this has already been published somewhere):

The main line in ECO E after 5.cxd5 exd5 6.Bg5 h6 7.Bxf6 Qxf6 is 8.a3 Bxc3+ 9.Qxc3 0-0 10.e3 Bf5 11.Ne2 Rc8 12.Ng3 c5 13.Nxf5 Qxf5 14.dxc5 b6 15.Bd3 Qg5 16. 0-0 bxc5 17.Bb5 a6 which was played in the game Seirawan-Wedberg, New York 1989, and now according to I. Sokolov 18.Ba4 is +/=.

However the temporary queen sacrifice 16.cxb6! gives White a winning advantage as far as I can see:

16.-,Rxc3 17.b7 Qxg2 18.bxa8Q Qxh1+ 19.Ke2
or
17.-,Rxd3 18.0-0! (18.bxa8Q Rxe3+ is not that clear) followed by bxa8Q

i'm quite surprised  to learn that Dearing is recommending 4. Qc2 d5 5. cd5 Qd5 6. Nf3 Qf5. This line does not make sense as a main choice for a repertoire, since it is rather drawish, and Black's best seems to be a draw. On the other hand, Kaufman recommended the Berlin Ruy, so maybe recommending endgame-openings is the new trend!?    
 
In NIC Yb 73, Tiviakov has a nice survey on this nimzo endgame, and his comments include "I had concluded that the endgame almost always favours White (don't forget the doubled pawns f5 and f7). The question is: is this advantage substantial or can Black neutralise White's initiative with acurate play?" and  "if you are facing a strong player, a draw is not a bad outcome at all!" Hardly a good choice if you need to win!
 
Black may well be solid here, but speaking as someone who plays both sides of the Nimzo, i think White's edge (albeit slight) is permanent and he can play on forever...

I think the endgame after Qxf5 is not so nice for black see the game Van Wely-Tiviakov !

Eddie

Look forward to your book on the Nimzo. I must admit I am surprised that you think 4...d5  5. cd Qd5 is holding up nicely- after 6. e3 I like the 2 bishops though I accept this is no refutation of this line. I think 6. e3 is better than 6. Nf3 whereupon I think the positions after Qf5 are okay for black. Why is 6. e3 not more popular?

PS. I really like your dragon book.

Hello,

Looking forward to new book. I think 4...d5 is best against Qc2 too, but am not too keen on playing it against lower rated opponents, because after 5p*p Q*p
6.Nf3 Qf5 7.Q*Q looks hard for white to lose, assuming this is line going to recommend? 
     Like the line you recommend against 5a3 since saw a game of Chris Ward's in BCM from 1999 or so.

Bye John S