I just got GPO about a week ago, and have already tried my hand at rendering a Mozart Symphony with it, and I have to say it does take some work!
However, it's fantastic to hear some of my favorite pieces being rendered with GPO. It is inspiring, and since I know I have GPO myself, and thus the ability to render music with the same realistic quality, it makes me feel . . . . powerful!
I'll feel a little bad when I post my first work with GPO because of the abundance of talent I see on this forum that far exceeds my own!