You see in magazines more and more rapid and even blitzgames taken serious and analyzed. I find this a sad evolution as I don't see what value this brings.

Carlsen played 1.a4 against Radjabov in the final blitzworldchampionship. I don't think he has thought for one second on the real theoretical value of 1.a4. Neither do i think that Carlsen cared about the real theoretical value of the Mason when he chose the opening. Carlsen knows from himself that even in a lost opening, he still can fight back in a blitzgame against a human opponent.

Besides I doubt many (top)grandmasters follow chesspubforum and are aware about what we amateurs are here discussing.

My knowledge of the current theory is that after 3...Qh4+ 4.Ke2, the old main line 4...d5 is fine for White, but 4...Qe7 is tricky and 4...Ne7, taking the sting out of Nd5 ideas, is probably best of all.  I remember agreeing with Brabo in a previous debate that 4...Ne7 gave Black an edge, so it would've been interesting to see what Carlsen's idea was against it.  

Interesting at any rate to see a top GM play the Mason, even though it was in a blitz game!