In the 2012 world championship he played 3xe5 and 3xd5 in the slow games, e4 in both the quick games.

Play where you are comfortable with.

I play the Morra Gambit.

E4 is more tactics and is easier to learn than d4 or c4 thats positional play.The reason why i begin with 1d4 or 1Nf3 too strenght my positional play and its difficulter for my opponent for his preparation.

k very interesting

Wait, which GMs are you talking about? Because if you mean older ones, than that is true because they didn't need it that much. But our generation today is competitive and have more resources, so they have to have good preperation to survive

I don't like d4 because it is easy for Black to dictate the course of the game, he can be sharp with Kings Indian, or Grunfeld. He can also be quieter, with some line of the QG.

1.d4 all the way for me, although in live chess (blitz) I sometimes play 1.e4 to provoke 1...e5 then 2.f4 a kings gambit is always fun!

Otb play I only use 2 weapons, 1.d4 and 1.b3 

Ianm not scared for the King's Gambit.If white plays 1 e4 he can play more Gambit style.I studie the opening but my endgame skills are better.

Ya, you are right.  Black spent too much time having his Queen run, and he only got to develop 1 peice.  That is why ...d7-d5 is not a good response to e2-e4.    But if White does d2-d4, Black is forced to do d7-d5 or else he loses a pawn or tempo.

In the Scandinavian there are four Queen moves. ( d6'e5'a5 and d8)theory,but better is Nf6 and after c4 play Gambit style with compensation.

I think e4 is better. Slightly. Maybe. ... However, I use d4 more often. :/

If you play 1 d4 you can play slow,with 1 e4 if you play slow you can have a big problem.If i play 1e4 a castle within 7 moves( normaly)and with 1 d4 i can castle on move 17 for example.

d4 isn't passive :)

1 d4 can be passive,but thats the fold of the player.I have also quick win with 1 d4.If you want a draw against 1 e4 you can play the Petroff deence.Iam not scared against the Knight Gambit Nxf7 inthe Petroff.

1e4-e5 2 Nf3-Nf6 and sometime white plays Nxe5 d6 and Nxf7 Cochrane Gambit.If you dont want to overrule in the opening than 1 d4 is a better choice.With white i have play 1d4,e4,c4,Nf3,b3 and for the joke 1 b4.