In my earlier blog "Can you believe your eyes", I discovered that the line 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 Bg4 6.h3 Bh5 7.g4 Bg6 8.Ne5 e6 9.Qf3 c6 10.g5 Nd5 11.Bd3 (diagram) is winning for white.
But, nearly the same position can occur through the Gunderam defense also, eg 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 Bf5 6.Ne5 e6 7.g4 Bg6 8.Qf3 c6 9.g5 Nd5 10.Bd3 (diagram). Now this position is different from its Teichmann cousin by just the placement of the h-pawn.
Question. Is black also lost in this Gunderam line ( you would assume so, since the position is the same, no ) ? Answer. No ! Black has an equal game after 10...Qc7 11.Bxg6 hxg6. If white continues 12.00 as in the Teichmann variation, black has 12...Bd6 (diagram).
In the Teichmann line ( with the pawn on h3 ), white now has the basic combination 14.Qxf7+ Qxf7 15.Nxf7 and the bishop falls as both bishop and rook are attacked. But in the Gunderam, this is not possible as the bishop has an intermediate check on h2, saving the bishop from its aggressor, eg 13.Qxf7+ Qxf7 14.Nxf7 Bxh2+. Black then even ends up with the better game !
So 12.00 is not recommend and white should choose the alternative 12.Rf1 ( with an equal game after 12...Bb4 )
So we see that, at least in this line, the Teichmann offers more chances for white than the related Gunderam lines. Expert knowledge is obviously required to deal with this !