The up board uses an atom cpu so don't expect anything beyond n64/ps1. You can try to use a refurbished pc from dell or hp, they are extremelly cheap.
FINALLY got Cyvern working, FINALLY got Rampage and Xenomorph working, But Outrunners and Turbo Ourtrun are either too slow or have bad sound. Still I'm happy I at least got Cyvern working. Room, I don't have room for tons and tons and tons and tons of PCBs. Believe me if I did I would.
Arcade systems aren't necessarily big. The Naomi is pretty small, there are versions of the MVS that are pretty small, the ST-V isn't that big, etc. You don't need "tons and tons of room" for those systems.
Neo carts are huge, and also climbing in price.Can't get Ninja Masters at a good price and it's not on any multi carts. I don't know how Naomi and ST-V carts are. It's more convenient this way. either way if I emulate or buy boards Devs aren't getting my money either way so...
The American Megatrends / ASUS P5QL-E Motherboard is pretty good for emulators. Real arcade hardware is better tho!
Pandora's box is just another emulation SBC and not the most powerful one. You can do much better with any motherboard with i3-i7, Phenom II even and JAMMA controller. It will be bigger and more expensive but not like really expensive. I had a MAME cabinet which used Phenom II x4 at 3.8GHz connected to 21" Sony BVM which i got for literally two beers as broken but was able to fix enough to use as RGB monitor for arcade machine, original case was removed of course. One guy asked if i want to trade it for a portable workstation class laptop and new iPhone 6 Plus as a bonus and i agreed instantly - that was 20 times more expensive and i really needed a good laptop.
My Pi is alot nicer now that I've used the Rom scraper....but even that is random It has no love for Ms Pac Man
I use the exe version of the scraper on PC and give it some commands so that it uses a different database and adds the missing games as empty entries in the xml file. It's more manual than doing it on the pi but I think it's better overall.
I'm using the gamesdb scraper so it's mostly manual. Weird that it has no entries for Dig Dug or pac man. I'm tempted to use Selph's scraper for time
FINALLY got Dragoon Might running I just need to map the buttons. I needed the Konami GX bios. I have around 400 games in MAME at the moment so the Pi 3 isn't AS BAD as it originally was. IF I can run games with the STV Bios I'm set