I wanted to try it today but I can find no way to have it trigger a VSTi. It doesn't show up as a controller or control surface and I can find no way to assign it. Likely pilot error but the documentation is pretty thin and I'm looking for a pointer. TNX.

It does not show up in preferences. The virtual controller appears as an input option on all instrument and MIDI tracks. Open the "virtual controller/keyboard" from the views menu. From there either use a mouse, touch or use CAPSLOCK or click the "Give All Keystrokes" to use the PC keyboard with the virtual controller.