Alex and Paul,
It is my understanding that "layers" of oscilators does in fact add to the number of notes used in all keyboards. Nothing in todays technology can change that. The Generalmusic sounds, if using one oscilator will be one figer played for each note of polyphony and if the sound is made from 2 oscilators (samples) then one note played takes away 2 notes of polyphony. Again, yamaha uses many 4 oscilator programs, Korg never can use more than 2 and I'm not sure how many Generalmusic sounds can use, but a good example of this would be in the Genesys's new brass 3 sound which uses many samples to create brass shakes when played hard and crecendos when played softly. there can be as many as 4 osilators in a sound like these and this could reduce polyphony by a lot. If Chris Anthony is reading this post, he could shed some more light on this subject.
George Kaye
Kaye's Music Scene
Reseda, California