I'm thinking 11. hg hg 12. g3, once alleged to be better for White, might be considered equal these days, but I don't know about "at least" equal ...
(By the way, a recent Chessbase DVD advocating the Exchange used a game Karjakin-Shirov for that line.)

I have a problem with the line  recommended in Ntirlis' 1.e4 e5 Repertoire.

The mainline given is 9.Nc4 Bxf3 etc, 

I had now two games where 9.b3 was played against me. Ntirlis gives only  "9.b3 is met by a strong manoeuvre: Qg7 10.Bb2 f6 -/+ ('Black is clearly better)".  I agree that Black is certainly fine.

My problem is that in those two games White played 10.Nc4 (the 'threat'' of taking on f3 is gone so the knight can move)

The first continued 10...f6 11.hxg4 hxg4 12.Ng5 Qh6 13.Nh3 Qg6 14 Ng5 and draw by repetition (although the engines say that White is better after 14. Kh2)

The second saw the 'improvement' Bc8 (after Be6 white has Nxg5, but Bd7 may be possible as well). I preferred Bc8 to Bd7 because I disliked giving White the extra option of taking on d7 after Nxe5 in some lines) .

I expected 11.Bg5 f6 and Bxh3 but was again surprised by 11. Nfe5 b5 12. Bb2 bxc4 13. Nxc4 f6 14.e5 where White does not seem to be any worse. 

So my question is simply what should Black play after 10.Nc4. Retreating the bishop looks better than 10...f6, but which move is better Bd7 or Bc8 and how to best deal with White's reponses (taking on g5/e5 or playing d4).