While I can't question anything my esteemed fellow member EclipseEye has pointed out, I do have one question:
Who can repair these things?
If it is a "copy job" and everything matches, this could be a non-problem.
If the board isn't a "copy job" (same traces, same chips, same power), does it have a manual with it? That takes the troubleshooting from "Average Arcade guy" to "Uber-Arcade Guy, with logic probe and other specialized skills.
What about sub-component quality? Did they use good or better piece parts? How can anyone tell? (It's not like you can see the K-Mart brand on the chip, right?) Did they use cheap knockoffs from China or South Korea for chips, or get good stuff? If they went cheap, your failure rate could be higher.
That would be the biggest hurdle as I see it. "I'm seeing a lot of "if" coming off this proposal."