Has anyone attempted emulation of the System 573 yet? (I know Zinc does Sony and Namco's PSX-based hardware) If so, any pitfalls?

For the later Bemani titles, I would assume the difficulty is primarily that digital I/O board. To make matters worse, all of the other parts are usually easy to find cheaply except for that board, which is still in service and high demand.

Anyway, I'm interested in looking into this further as long as there aren't any other known major obstacles or protections.