I agree with William totally. VSL is capable NOW of producing realistic orchestral performances (but I think you have to pick pieces that suit it best) - emulating an orchestra with a computer is a terrifically complex task - VSL succeeds with this, so this enables a new breed of talented musicians to emerge - 'Orchestra performer/programmer' to give it a crude title-- Jay Bacal is one of the pioneers - but he wouild not have bothered to have done it unless he knew the tools were available/capable to do it.
I think Jay with the Rite of Spring has set a benchmark - but there are equally realistic mock-ups by other 'performer/programmers' on the demo page - just not with the length and complexity of Jay's work.