punter wrote on 07/06/11 at 20:25:55:

You might try 6.f4 here:
a) 6...Nc6 7.Be3 d6 (b5 8.Be2 Bb7 9.o-o Rc8 10.Nb3 Nf6 11.e5 b4 12.Nb5 axb5 13.exf6 gxf6 14.Bxb5 unclear) 8.Qf3 Nf6 9.o-o-o is the 6.f4/7.Be3 attack of the Scheveningen; Black has already played a6 and Qc7. There are a few deviations White has to deal with.
b) 6...d6 7.Bd3 b5 8.Qf3 Bb7 9.Be3 Nf6 10.g4 is similar.
c) 6...b5 7.Bd3 Bb7 8.Qe2 d6 9.Bd2 with more or less the same idea - castling queenside and storming.

White can't claim an advantage in all lines, but play looks very interesting.
A related question: how to meet 5.Nc3 b5 ?
I haven't found anything yet; Black does amazingly well.

Eric might be right that 5.Bd3 is best. I am not sure of 5...b5 6.o-o Bc5 though, even if this is very rare. I suppose that shows my lack of understanding.
IM Van Delft in his Schaaknieuws series recommends 5.Bd3 too with three main lines:
a) 5...Nc6 6.Nxc6 dxc6 7.Nd2 e5 8.Nc4 Nf6 9.Be3
b) 5...Bc5 6.Nb3 Ba7 (Be7 7.Qg4 g6 8.Qe2 d6 9.a4) 7.Qg4 Nf6 8.Qg3 d6 9.Nc3 following the game Markgraf-Lanka, Hamburg 2007. Van Delft suggests 18.Rxh6.
c) 5...Nf6 6.o-o Qc7 7.Qe2 d6 8.c4 g6 9.b4 Bg7 10.Bb2 Svidlere-Landa, France 2002, is a rare sideline worth investigating.

What do you hate the most as Kan player ?
I don't have any problems vs Taimanov as English Attack is not only good but also gives me chance to bust some lines recommended in very popular books.
Vs Kan there is no English Attack. I don't like c4 as imo it's equal and I always felt that hedgehog positions are pleasant for black to play in practice. The problem for me is the main line:
1.e4 c5. 2.Nf3 e6 3.d4 cd4 4.Nd4 a6 5.Nc3 Qc7 6.Bd3 Nf6 7.0-0 Bc5 8.Nb3 Be7 9.f4 d6 which frankly looks like worse sheveningen for white to me.
I would much prefer to have some more concrete play or some pleasant endgame which white can press (even if drawish). Is there anything you really don't like to face as Kan player or have some favorite weapon as white vs it ?