I don't know; I recall that one of Keres' collected games was with 2.Nf3 d6 3.b4, and that he had good things to say about it.  Ultimately I don't think that either move is quite sound, but each subjects Black to problems that he may not be familiar with. 

I believe 2.b4 is better than 2.Nf3 d6 3.b4 because the knight on f3 greatly reduces White's attacking options, since now Qg4/h5 is not possible and White cannot play Ra3-g3(h3) to lift his rook to the kingside.

But why are you choosing the Wing Gambit over say the Open Sicilian or even the Alapin?

Oh ok I've asked about the Wing Gambit in the past. Now I have a more general question. Is there any advantages of playing the delayed wing gambit over the normal?

So...
1.e4 c5 2.b4!?
or
1.e4 c5 2.Nf3 d6 3.b4!?

Objectively speaking these kind of gambits are nothing more than surprise weapons. But some high level CC friends of my were play the normal lines and trying to find the best way to go for black and came up with ...3.cxb4 Nf3 4.Nc6 and this looks good to me. Of course if asked I can show one game that was played between the highest 2 players it was a good match that ended in a draw. I'll be graceful for any help as I'm thinking about trying this in a tournament game soon!