Synth Project's output of controllers is astonishing - he's continually making dedicated hardware MIDI control for software synthesizers - something you really have to try to feel the full power off (see the impOSCar controller fr'instance).
His latest creation is called the Diva Controller and works with the U-HE Diva synth and is a real monster.
However, dont expect to be able to buy one anytime soon. The man behind Synth Project makes one-off's not mass production units - though you can sometimes persuade him to make you something...
Can you record a full track with it and an iPad?