Lisa used a Roland Fantom X-8 during her time with the band. Apparently she wanted to keep her weapon of choice a secret (or just didn't want to advertise), since the back logo was covered in black tape after a certain point.
The Fantom-X series ran from 2004-2008, and had features including 128-voice PCM synthesizer, 16-track sequencer, dynamic pads, stereo sampling, and full on-screen editing. It was also the first synth to feature a full-color LCD screen.
[product page (discontinued) | wiki]