Yamaha DTXpress/DTXplorer/DTXtreme

Hi,

I am planning on buying a DTXpress 2 next month, and I have a few 
questions left ecpecially about the up and downloading of userkits to 
and from the brain. The salesperson told me it was impossible to 
upload kits to te brain, but here (and on the DTXpressions site) I 
read that it is pretty easy to opload kits to the module. My 
question; Are these kits a collection of (edited?)voices which are 
built into the DTXpress or can one also upload new voices (based on 
wav files or something) to the brain?

Thanks,

Joep