The databases on the net that I refer to have very few games in which Black plays the Bishop sacrifice that Fine regarded as sound (in the 4.Bf4 line) - 

1. d4 Nf6  2. c4 g6  3. Nc3  d5  4. Bf4 Bg7  5. e3 0-0 6. cxd5 Nxd5 7. Nxd5 Qxd5  8. Bxc7 Nc6  9. Ne2 Bg4  10. f3 Bxf3!?  11. gxf3  Qxf3  12. Rg1  Qxe3 etc.

Since it seems that for now I like 4.Bf4 against the Gruenfeld, I would appreciate any insights into the current thinking on this sacrifice line. I possess no books on the Gruenfeld (yet).

In the few games I could find, Black sometimes manages to win, and so does White. Difficult to see whether the position is strong enough for Black. Playing White, with the Bishop for 2 pawns, I would be a bit worried about the wreckage on my kingside.