Question

The idea is that I can add a VST plugin that can alter the MIDI data stream generated by Notion before it enters the VSTi plugin. This could eg be used to add some random variations.

If the VST could also receive input from external MIDI devices as well, you could use it for real time changes in playback mode.

The VST plugin I'm thinking of are ReaJS and ReaControlMIDI which are part of Cockos' ReaPlugs bundle.

Answer 1

Cubase has a similar feature.  Very useful to introduce random or somewhat programmed effects for velocity change or timing.  I would like to see some basic internal MIDI mods (randomize or modify note length and velocity, for instance) instead of having to load a third-party plug-in.

Answer 2

Wouldn't say no to built-in randomization. But I like to be able to customize things :)

With a plugin you could do more, but I'll take randomization as for starters.