I'm a long-time Finale user, but I have never really gotten in to Human Playback, using mainly the Garritan sounds, and being fairly happy with the playback provided with Human Playback.  It at least sounds okay until live players play the music.

I am now augmenting some of the sounds from Garritan with some East West sounds using the "Play" engine.  I decided to actually spend a lot of time trying to figure out how to utilize Human Playback, and it has become pretty frustrating.  

For one thing, EW uses "controller 11" for much of the volume.  I thought I could set up a key switch midi number and make the second "Action" dynamic: velocity plus controller 11.  That pretty much did nothing for the sound.  I tried pretty much all the options, and I had the best luck with the second "Action" being dynamic: Velocity only.  I can actually hear some crescendos and diminuendos with this setting, but the timbre of the instrument doesn't change much.  I also tried using ONLY Controller 11 - and that seemed to be doing something, but the volume of the instrument diminished greatly.

I then started reading about the midi tool.  I've never really used it - relying instead on Human Playback.  I found that I could apply the human playback within the midi tool, then I could go and MANUALLY change all the info for controller 11.  This works nicely, and the sound is more or less realistic, but it takes FOREVER!  I can't find a way to make the smart crescendos actually affect controller 11 info.  Anyway, this is where I'm at now.  I have found out a lot about human playback in the last two days, but it is still very puzzling.