May be SD1 sampler has very big problems that need to be fixed. When I play certain tabla samples on the computer they sound very natural. But when the same samples were played on SD1 they don't sound that natural. I don't know exactly what are the differences, but they sound different (and computer sounds are more natural).
By the way, my computer is just a normal one without expensive sound cards or speakers. SD1 is a "professional keyboard", so, shouldn't its sampler create better sounds than my ordinary PC?

Another thing. Not only SD1 can load much less than 16GB of data, there is a limit on individual wave file sizes. For example, it cannot load a 300KB wave file. It says (something like) file size exceeds the limit.

-Dimu