Finale's human playback improvements in 2005 are a big improvement over the earlier version, but I still think out the output as a sketchpad of your piece. To get the kind of results you hear in the many demos posted requires a lot of tweaking of midi data easily done in a sequencer. Explore Finale's midi tool and how to edit things like velocity data. Let HP incorporate your midi data into it's interpretation. This is where Overture has an edge over Finale. Their piano roll editor is much easier to use.
I'll second that...Overture da bomb! Da Man! The exquistely crafted piece of notation software that's perfect for GPO playback! And it's getting better still...see the Geniesoft forum. Good stuff in the pipeline. Very good stuff.