I play various BEMANI games and from time to time I also play some Jubeat. I was not satisfied with DJ DAO boards in other controllers but I could possibly be ok with some of those. The FB9 one though is really bad compared to arcade experience and I simply did not want to play Jubeat at home because of it. Not great when you paid a lot of money for it. But then I stumbled upon zhousensor's P4IO, bought it and it changed the whole experience. No latency, it's not drunk as the DJ DAO board and you can even press all the notes you manage to press at once.
Playing on stock FB9 is a recipe for frustration, and yet I did so for almost three years before finally picking up one of these, so believe me when I say this restored my will to play Jubeat. You could *maybe* pay slightly less for this by going through a proxy service for overseas storefronts, but yubiparts makes the process about a hundred times easier.
Painless, quick delivery, relatively easy to install, and worked perfectly once I got all the settings correct. Definite must if you're planning to play on a Jubeat con. Eliminates the input lag and the frustration of missing patterns on higher charts from an unregistered button press.