Ive built several MAME cabs in the past, I even had one with an A500 mobo wired to Jamma. Very good for those Amiga based arcade style games, Speedball2, Rodland... ect.
I always use a Win/PC as the basis of a MAME cab, it's less hassle than exotic hardware and has loads of emulators. Full size arcade cabs are great if you have plenty of room, which I no longer do.

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Now I'm happy with my little GP2X to do the lot.