Hi Metcam,
I have no idea about technical stuff but do you really believe that a voice sample from a keyboard would sound also as good on another keyboard just by loading it through YEM?
My opinion is that the different 10+ kilos kind of stuff (plastic,software and hardware) of each model, play a huge role on how a sample will finally sound (good,better,best).
I have seen a video demonstration from styles2psr of how he samples his voices in YEM for his s970.
T5 and Genos can do more things with YEM than the psr s, or you just want to be able to load voices from a Genos to an sx900?