Someone a few posts down was saying something about "gm midi" sounds being different then the Solton? That it uses 3 channels up for each sound?

Does this mean for example that all the demos I've heard showing the SD1 sound, are not going to be the same when I play a midi file through it? In other words, can I play a grand total of about 4 instruments from the "premier" Solton sound, and then have no more channels for midi?

I'm a little confused here, and I would like to understand this before I buy.