Ok, let me back out of this gracefully. It doesn't surprise me at all that UD and others can play the Roland 4-way scat program (one of my favorites as well) masterfully. Those that can handle the scat program are good candidates for using the megavoices live.

For contrast, consider a triple-strike piano. If your velocity is on the wrong side of a velocity boundary (e.g., 65 instead of 64) you get a slight timbral variation. In the case of the scat, you get a wrong syllable--which is more disturbing. In the case of a megavoice, you might get a drastic change of timbre--e.g., a mute instead of an undamped string sound. So until you master a megavoice, expect to be a jarred by some errant timbres.