I have managed to play the mega histring guitar, 12 string and some of the bass sounds live - listen to some of the demo's I put together live on the tyros at
http://www.psrworld.com/tyrosdemos.htm#songs The trick was to split the keyboard and map the same megavoice to both halfs, but octave switch the upper half so as to access the effects. Then adjust the velocity sensitivity so only to trigger the switched samples on heavy playing. It works with a few of the sounds since these only contain 3 layers, the steel string guitar is too complicated though to play live and needs to be programmed with constant velocity and then the velocities adjusted afterwards. Theoretically it could be done in realtime using some form of live midi data processor though to remap the velocities and zones of the keyboard, something I might try in the future.
Simon
SVPworld
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Simon G.K. Williams
simon@svpworld.com
Creative Music & Multimedia
http://www.svpworld.com________________________