Greetings All,
The endgame after 7.Qf3 Bg6 8.Bxf6 Qxf6 9.Qxf6 gxf6 is certainly better for White but it is extremely difficult to get a full point, I must admit. Moreover, if White is getting to relaxed with his advantage the things might easily get even worse – once I comfortably lost to Jonathan Parker in Hastings Challengers 1994.

Then, some years later, in Polanica Zdroj 1997, I put my opponent, Miroslaw Grabarczyk, under serious pressure but he defended well and got half a point.
Nevertheless I believe that White can comfortably maintain a small advantage after 7. Qf3 but an extraordinary technique is required to win the game. However, let’s take a look at this line from Black’s point of view – you must really enjoy to keep defending to play this type of position, hoping to get not more than half a point.
As to the line 7. Qb3, it looks less attractive for White since Black has not only 7. ...Qb6, getting a similar endgame – such options as 7. ..b5 and 7. ..Nbd7 are also playable.
Merry Christmas and Happy New Year!
Ruslan