I learned recently how to record the output of MIDI FX plugins in Logic:
1. Enable IAC Driver in /Applications/Utilities/Audio MIDI Setup.app
2. Add MIDI FX plugins to your Software Instrument track to give it the required randomization, modulation, arpeggiation, etc.
3. Change the instrument on the track to External Instrument and set the MIDI Destination to "IAC Driver Bus 1"
4. Create another Software Instrument track and arm it to record; enabling an instrument on this track is optional.
5. Hit record; the effected MIDI data will be recorded.
Seems straightforward enough and doesn't require installing any additional plugins. But I have a few questions:
Is it safe to leave IAC Driver enabled?
By "safe" I mean: Will leaving it enabled cause any MIDI timing issues, or timing/buffering issues in general?
Considering how useful this method is, why is the IAC Driver normally disabled?