I'm a big fan of Mame and all, but it would be easiest and cheapest to just get the real deal and swap the boards.
I disagree. If what I want to do can be
easily done with a pair of PC monitors and a typical dual VGA video card, then there must be a way to do the same thing with arcade monitors. If one of those newer dual VGA cards could output 256x224 (maybe with the help of Powerstrip?) then I would be almost there. Set that to a vertical span of 256x448 and that would be perfect...the only thing left would be getting it to do 15 kHz for 2 standard resolution arcade monitors.
Mame isn't any more future-proof than real video games. Eventually, Mame might not be developed any more, and the way PCs are changing nowadays, you might have the same difficulty finding a MAME-compatible PC as you would finding the original boards. At least, original boards are usually repairable.
X86 isn't going anywhere any time soon. It is
far more future-proof than
any arcade board. There are millions upon millions of PC's out there right now that can run MAME, with no end in site in the near future. Compare that to the production runs of the specific Nintendo boards being discussed here. Emulation isn't going to die; if not MAME then something else will take its place. I don't see Nintendo or anyone else taking up production of their old arcade boards any time soon though.
Yeah, I'd like to have the real arcade boards and I try to keep an eye out for them, but I want a working emulation setup as well, for reasons I have mentioned above.