The Motif does have expanded Articulations that can be incorporated into the voice elements and triggered in numerous ways.

Megavoices are more suited to Arrangers for the STYLES. There are no Styles on the Motif but the ARPS do use ROMS that seemingly use MEGAvoice technology although the spec sheet does not list x amount of Mega voices

6000 ARPS have to use that technology in some manner as all the elements for the Megavoice are there. Squeaks, slaps,string dynamics, on and on.

Programing voices is an ART and for many a hobby unto itself. I try to buy voices out of the box, Rarely do I even get on the Element level and tweak.