Does it (7.a4) have enough "bite"?
So, you suggest studying the Khalifman book (Kramnik rep.) ?
Both 4.Nc3 and 7.e4 are gambit-style. Just what I argued against.
(Also in the Avrukh-book, there are a lot of forced lines up to move 15-20sg, where I have to remember "only" moves in sharp positions, while I can't afford to spend so much time studying one opening which, incidentally, I have never had to face in practice yet.)
TN wrote on 02/15/10 at 12:24:07:
7.a4 was recommended by Khalifman if I recall correctly, and seemed like a good choice, at least if you want a reliable long-term weapon against the QGA.
Personally, I've always thought that 7.e4!? was an interesting and quite effective surprise weapon. There are a few routes to equality for Black, but the line is old and forgotten and if you are prepared in the critical lines, then your opponent's ride will probably be bumpier than yours.
Otherwise, there's something to be said for playing in gambit style with 4.Nc3, which leads to quite interesting positions.
7. a4 has significant bite, and is far from being harmless. There's a reason it's been played by several super GMs.
That aside, 7. Bb3 is still probably the way to go.