[vardump]

An FPGA can be 100% hardware perfect with practically no extra processing cost. The potential is there, even if it's not initially exploited.

CPU based emulation will require a fairly powerful CPU just to emulate SNES. It's pretty expensive to emulate hardware in 180-190 ns increments.

[pclmulqdq]

This isn't quite true - you lose some of the weird analog stuff that may have happened. On a well-designed board, though, you can get essentially perfect cycle-accurate reproduction.