I always played 3.Nc3 dxc4 back when I played the Slav, and generally liked the positions I got.  Also, Shipov (or Shipkov, can't remember) gave this move an exclam back in their book Winning with the Slav.  Can it really be so bad?

Also, cut James some slack; no matter what lines he chooses to cover in a repertoire book, someone will be unhappy...

Genghisclown.
Think you'll be surprised. Plenty of fun to be had with Nc3 ...dc4.
Dont be too despondent about the black game.

Perhaps not as much 'what is wrong with ...Nf6' as 'why not play ...dc4?' A half-full glass. Very slav behaviour  to take the pawn if possible I reckon.

inn2
You always appear to know your stuff. Any suggested last-minute sources in other lingos for James?

The problem with 3.Nc3 Nf6, from the point of view of a 'pure' Slav repertoire, is 4.e3, when 4...Bf5 is generally thought to be unsatisfactory because of Qb3 (although I can never remember whether White is supposed to flick in cxd5 first  ).  4...g6 is a line of the Schlechter also generally thought to be good for White, while 4...a6 and 4...e6 transpose to the Chebanenko and the Semi-Slav respectively.

It all sounds very interesting; when is the book likely to be published, James? 

Interesting choices James.
Seems like the philosophy of this upcoming book is about maintaining a tense + solid game. 

White players probably wouldn't complain about facing these lines since few simplifications, but Black players can be content with solid-ish positions too. Suspect your lines approximate to "=" in practical chances for OTB games, even though they may well turn out to be "+=" if theoreticians like Khalifman have their way...

not so sure about 3. Nc3 dc4 though (but okay its consistent for a repertoire), and i suppose its going to be 3. Nf3 Nf6 4. e3 Bf5 ? or is it the new fangled 4... Bg4?

Anyway, good news to hear about Qb6 exchange lines. Finally someone treats them seriously!

hi james, what is recommended against dutch slav 5. a4 Bf5 6. e3?

and i repeat: one can never have too many slav books 

Play the Slav is a 'pure' Slav repertoire, i.e there is nothing on the ...a6 Slav. I would enjoy writing about that too, but I suppose that's best left to Bologan for the time being...

In the main line, I have chosen the variation Ivan Sokolov has done so much to develop, 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 Nc3 dxc4 5 a4 Bf5 6 Ne5 Nbd7 7 Nxc4 Nb6 8 Ne5 a5. The Morozevich line (7...Qc7, followed by a ...g5 Bayonet a little further down the line) is holding up reasonably for Black as far as I know, but strikes me as too unstable to cover in a book which I hope might remain of use to the reader (and to myself!) for rather more than a year or so. I've enjoyed exploring the Sokolov line, which neither kills the game off (like Kramnik's bishop-shuffle against Topalov) nor launches it into fearsome complications (Morozevich). 

A couple of other highlights of the repertoire - 3 Nc3 dxc4 (Tracke, I hope this is welcome?)
and a fairly aggressive repertoire against the Exchange Variation, including 3 cxd5 cxd5 4 Nc3 Nf6 5 Bf4 Qb6 (already briefly discussed in John Watson's Mastering the Chess Openings Vol 2).

Since the book isn't quite finished I'd better not say too much more for now, but I hope that whets the appetite, and reassures that this is by no means a recipe for a quick and easy draw for Black...

Yes, let's all exclusively play the exchange for a year or two, drawing most games, but winning some, and we'll hardly ever have to face the bloody thing again...