Over time I discovered various conflicts between the different Garritan Libraries with the techniques in Human Playback.

Here is my attempt at building a stronger filtering system, and coaxing a little tighter sound out of the new GOS strings (Changes the CC119 offset to attack at a higher initial amplitude instead of swelling into the note). 

It's not guaranteed to catch everything on the new filters, but it's worth having a look if you are plagued by issues after having installed GPO5.  Now you should be able to go back to the Legacy strings if desired and not get the annoying key-switch conflicts.

https://drive.google.com/open?id=0B-9pjh4Xl8gsUFZYUm80d1lCT1U

I'm now able to mix and match the new Garritan Orchestral Strings with the Legacy Strings.

Hopefully the set saved as part of the score, and you should be able to import this profile to your own setup by going into "Edit/Preferences/Human Playback" and toggling the "Attach to" check box off.  If that doesn't make a copy of the profile in your Human Playback Preferences Set, please let me know and I'll make a bit of xml avilable that can be pasted into your  "preferences.humanplayback.xml" file.