Hi Geeztown. If you use the "External Instrument" Software Instrument, you can definitely use all the MIDI FX to trigger your physical hardware. I wrote a full article on using this instrument with MIDI gear for the latest macProVideo/Ask Audio magazine. I'm guessing (haven't tried it), that since MIDI is being sent to the outside world this way, and if the receiving device can be set to send what it receives back out through it's MIDI Out/Through, MIDI could theoretically come back into Logic! :). I'll experiment with this and see if it's possible, but yes, you can definitely use MIDI FX with external hardware.

Thank-you Rounik! :) One more though Geeztown ...many virtual instrument have the ability to assign standard MIDI continuous controllers to take control over various parameters. ES2 for example allows you to do this in it's router. The MIDI FX Modulator can definitely be used for this by setting it's "To" parameter to the same CC# you assigned to the parameter in the synth.