I do not believe that the variant 1.e4 e6, 2.d4 d5, 3.e5 c5, 4.c3 Nc6, 5.Nf3 Qb6 gives White any theoretical advantage, in none of the pathes 6.Be2, 6.Bd3 and 6.a3.
a3 is pretty annoying for Black after Qb6.But it isn't as effective against 6.Bd7.7.a3,f6 gives black an easy game.
Wolfgang Uhlmann has shown that the variant 6.a3 c4!, with the idea of a fast f7-f6 gives Black a good game.