Hi out there

I've played an OTB-game vs the QGA / Smyslov Variation some time ago (notation below). I'm still thinking about the opening and I wonder why it is not more popular. The score in my database is good for white, but I do not really find a reason why.

[Round ""]
[White "me"]
[Black "theotherguy"]
[Result "1-0"]
[Eco "D25"]
[Annotator ""]
[Source ""]

1.d4 d5 2.c4 dxc4 3.Nf3 Nf6 4.e3 g6 5.Bxc4 Bg7 6.O-O O-O 7.Nc3
Nfd7 8.Qe2 Nb6 9.Bb3 a5 10.Rd1 a4 11.Bc2 Nc6 12.a3 Bg4 13.h3
Bxf3 14.Qxf3 e5 15.d5 Ne7 16.e4 Nec8 17.Be3 Qd7 18.Bc5 Nd6 19.Qe2
Nbc4 20.Bd3 Na5 21.Rab1 Nb3 22.Be3 Nd4 23.Bxd4 exd4 24.Na2 Rae8
25.Qc2 Re7 26.f4 Bh6 27.Rf1 f6 28.Rbe1 Rfe8 29.Nb4 g5 30.Qf2
Nxe4 31.Qxd4 c5 32.Qc4 b5 33.Qxb5 Qxb5 34.Bxb5 cxb4 35.Bxe8 Rxe8
36.axb4 Bf8 37.fxg5 fxg5 38.b5 Bc5+ 39.Kh2 Bd6+ 40.Kg1 Bg3 41.Re2
h5 42.Rf3 h4 43.b6 Bf4 44.b7 Bb8 45.g4 hxg3 46.Kg2 g4 47.hxg4
Nf6 48.Rxe8+ Nxe8 49.Rc3 Nc7 50.d6 1-0

Some short remarks / comments
I was "on my own" after move 6.
Blacks 12...Bg4 is new. I do like it more than 12...Bd7 played in he stem game by Smyslov
21.Rab1 is a weak move. Much beter was 21.Bxd6
25.Na2 (?) simply was panic. I thought that Nb5 simply would loose the knight after ...Nb8 and ...c6
30.Qf2 is a nice one. But I have to admit that I simply wasn't able to calculate everything. That was totally "burning bridges"
36.gxf4 instead of 36...Bf8 (?) should be about equal
There was a perpetual after move 40
After 43.b6 it was over. That move was possible one move earlier.

Conclusion:
- Black has a clear plan and no weaknesses
- The moves  are easy to learn
- Black (more or less) plays the same moves in all the lines of this variation
- Black seems to be extremely safe in this variation

Everything mentioned above seems to indicate that this line is perfect for a repertoire for black, if a positional player.
So: Is there a line that leads to concrete advantage for white, or is the Smyslov-Variation simply out of fashion?