Managed to get the Vorb GUI loading in an FX track. Some (essential?) buttons are missing, like the XTC-specific Direct Output and XTC/DSP usage button. I could not get it to receive or transmit audio. It can neither be used as an Insert in Multi-FX.
For those who don't know about Vorb - we're trying to get an SFP synth which was
not designed to work in XTC to do that anyway. So no worries if it doesn't work, call it a style excercise

)