The problem with the earlier version was that you couldn't assign samples to the different tracks of a single instance; all the midi channels would play together with the same instrument. (Unlike the Edirol Sound Canvas). That is, the "multi" would not work when triggered by live incoming midi.

(At least I couldn't get it to work - I haven't checked the latest version 2.75 yet.)

The new version (version 3 beta, that is) works fine, so you can assign an instrument to each channel, mute,solo, etc. from within VSampler 3.