Last post indicated that the "More than Hara Kiri" attack is wrong, and I recommended white to play the simple 5.fxe4.
Black now may wish to exchange the knight with 5...Nxe4 6.Qf3 Nxc3 7.bxc3.
After black's simple 7...e6 my book, I recommended 8.Qxb7, regaining the pawn, but I believe the continuation 8...Nd7 9.Nf3 Rb8 is better for black, eg
a/ 10.Qc6 Bxc2! 11.Bg5 Be7 12.Bxe7 Qxe7 and both 13.Bb5 and 13.Rc1 fail to equalize
b/ 10.Qxa7 Bxc2! and 11.Bg5 and 11.Qa5 offer not enough.
c/ 10.Qa6 Bxc2! is even worse for white.
So I started looking for an improvement to 8.Qxb7 and believed 8.Bd3 might be better. After the simple 8...Bxd3, white has the choice between 9.cxd3 and Qxd3.
d/ 9.cxd3 and black has the killer move 9...Qd5! with obvious advantage
e/ 9.Qxd3 complicates things a bit more for black, but still does not address white's lack of pieces.
Bottomline - exchanging all pieces in the suggested Vienna defense is a strong defense and leaves white with a bad position.