Hi Grover --
There has been a little discussion in the Genos Voices part of the forum. That's a good place to ask about overlap, i.e., expansion vs. factory preset.
A few users determined that the alto and baritone sax expansion voices are already in the Genos.
I have the S970 Church Organ pack -- which does load and play on Genos -- and the Female Vocal pack. The Female Vocal pack does not overlap. There is some overlap between Church Organ and the preset Classical organs. But, the Church Organ pack has several unique voices, so I keep it loaded and use it.
Hope this helps -- pj