What's the opinion on those Dreamcast GD-emu boards?
What about the 3DO replacement one? Better yet, how is 3DO emulation in general on PC?
Emulation is probably not very advanced, I haven't checked. I have the USB one for the 3DO, it works fine. The same Russian guy makes the USB one for the Dreamcast, a competitor to the GD EMU fellow. His is expensive, but he fills the orders pretty quickly.