According to Mitchell's official site, she uses a Roland VG-8. "In every gig since the 1995 New Orleans Jazz Festival, Mitchell has used the VG-8, using its effects to build a guitar sound reminiscent of her Hejira era."
What about the VG-8? You're not using that anymore?
"No. I sold it out of desperation. But I would have liked to have kept it 'cause it was a useful tool. I actually liked it a lot. I thought it was a really great thing."
My main electric banjo is a custom Deering Crossfire. It has EMG pickups and an EMG preamp. I’ll also use it to trigger synthesizers with a Yamaha MIDI pickup connected to a Roland VG-8 guitar synth and a Roland GI-10 MIDI interface.