The ones from version 5 and 6 are more accurate than the older ones (going back up to twenty years ago). The version of the library where the instruments appeared is listed in the manual and in the Info tab of each instrument.
Paolo
Agreed. v4 and prior is prob only really good for flourishes and colors. It's still nice to have it included though. The v5 and v6 instruments are prob more up to current sampling standards however.
Also don't forget, a lot of world instruments don't have a lot of dynamics in real life either. So don't let the fact that some instruments only have a couple of layers put you off.