External MIDI track vs External Instrument plugin?

It depends on your setup, but also on the exact demands you have. If you plug your hardware synths directly into your audio interface, and you don't want full control over all MIDI parameters, then use the External Instrument plugin.

But if you have all your synths summed on a mixer, then there's little point in using the EI plugin. Also, if you intend to send Program Changes to the synth from a list of names, or MIDI Pan or MIDI Volume, or use it multi-timbrally, none of these things work through the EI plugin. Then you use an External MIDI Instrument and maybe an Aux to bring the audio back into Logic.

Christian

Because in the old days, sequencers (which is what software like Logic was called) didn't have any audio channels at all, no plug ins, no audio instruments, nothing but midi tracks. All you did with the software was the music creating/editing work only at the level of midi information - all the actual sounds were only ever triggered externally on all of those racks and racks of synths, samplers, drum machines and whatnot that you used to see in prehistoric studios. So all of the audio processing fx - reverbs, delays, choruses etc were all external boxes too. Not a single audio source was ever plugged into an audio interface to come into the computer - people used mixing consoles with actual physical inserts and sends and returns and busses to route all of these things together. And the final results were not bounced, a stereo mix was recorded to DAT, or some other format.

So, to return to your question.. Some people probably still work this way, or work in a hybrid fashion of the old-school way and the newer way of working. So in this case, it makes perfect sense under some circumstances to just use a plain old vanilla external midi track, if the audio from the sound source in question (a synth or whatnot) is just going to an external mixer and not back into the computer as audio.

The above answers are pretty comprehensive, but just for what its worth, I still use my Akai Z8 sampler for some projects and tend to stick to using the external instrument tracks set to different MIDI channels because I'm used to doing it that way from back when I started out with my Atari/Cubase and it works just fine for me.

When I'm sure I've come to the end of the line with what I want to do, I record the individual tracks as audio - perhaps not the most elegant way of working, but its what I'm used to. Obviously I have to decide whether to use the Z8's FX and record them or use Logic's FX, but therein lie a lot of possibilities.

That would depend on your recording set - up. Several times over the years, I have switched back/forth from using all external synths, to all virtual, and sometimes a mixture of both. Depends on the project. Currently I have two Yamaha instruments, (motif and Tyros 3). They blend very well together and give a nice cohesive 'wholeness' to the music.. I'm really getting back into pushing buttons, and turning knobs. Emotionally if feels better to me to have hardware around.