With regards to the FPGA approach, I think the issue when you are talking about a lot of games is the complexity and magnitude of that undertaking. JROK spent considerable time reverse engineering the Williams platform, and tweaking the design of his Multi-Williams board to get the game timing as close to the original as possible. Imagine the effort to implement just the set of games on the 60-in-1 for example, where you have a variety of platforms: Stern, Midway, Capcom, Nintendo, etc.. If you focused on one system, such as Capcom CPS-1, you would have more bang for the buck, but there is no way an FPGA implementation will ever touch the size of library that a basic MAME setup is capable of running, and emulating quite well.