I had some problems lately playing against a strange Vienna-like line, occuring after 1.d4 d5 2.e4 dxe4 3.Nc3 Bf5 4.f3 exf3 (diagram).
White has two options now : 5.Qxf3 and 5.Nxf3. The Ryder-like continuation 5.Qxf3 seems more direct as it attacks both the pawn at b7 and the bishop on f5. Unfortunately, black has the simple, but very effective 5...Qc8 and white has difficulties in creating an attack
So I advise it is better to stick to 5.Nxf3 (diagram), with followng options :
a/ 5...Nf6 6.Ne5 (Gunderam defense)
b/ 5...c6 (A Karo Cann without Nf6) 6.Bd3
...b1/ 6...Bxd3 7.Qxd3 (=) and white has a nice lead in development
...b2/ 6...Bg6 7.Bg5 (=)
...b3/ 6...Bg4 7.h3 (+=)
c/ 5...e6 6.Bd3
...c1/ 6...Bxd3 7.Qxd3 (=)
...c2/ 6...Ne7 7.Bf4 (=)
...c3/ 6...Bg6 7.Bxg6 hxg6 8.Qe2 (=)
d/ 5...Nc6 6.d5 (+=)
e/ 5...Ne7 6.Nh4
The alternative 5.Qxf3 Qc8 6.Bf4 (diagram) also does not seem to bring any advantage for the attacker, eg 6...Nf6 with complete equality.
So it seems that this is a completely different line, as black has a much simpler game defending. Most lines seem to equlize rather quickly. I will remember this option if someone dares to venture a Blackmar Diemer against me !