Has anyone experimented with Galkin's move in the 5 Nf3 line of the Smyslov Caro?

1 e4 c6 2 d4 d5 3 Nc3 dxe4 4 Nxe4 Nd7 5 Nf3 Ngf6 6 Ng3 b6!?

Instead of 6 ... e6 followed by 7 ... c5 or the immediate 6 ... c5, Black puts in a move to help ease the development of his problem piece.  In principle, I don't see anything wrong with this: it avoids mainstream theory and serves as a decent waiting move, Black's position is sufficiently solid that he doesn't have to strike with c6-c5 immediately, Black will likely want to play b7-b6 at some point anyway, b7-b6 often helps make the c5 break evn more powerful when it does come.  At the same time, I don't think 6 ... b6 completely revolutionizes the theory of the Smyslov Caro, but are there any real flaws or reasons why this isn't played too often?