In past versions of Logic, with the way Multi instruments were designed to be used, I did not find them helpful. But the recent updates and upgrades have been much more practical for my work flow! Now I’m allowed me to insert MIDI data on each voice of the multi, which I could not seem to do in past versions. Now it allows me to use the Multi in a number of ways.
This video shares tips, and shows the routing for Omnisphere in Logic Pro X as a Multi instrument. The principles can be applied to many other Multi instruments (EXS24, Drum Kit Designer, Massive, Battery, others).