Users should beware of possible incompatibilities between versions. I loaded the previous "beta" version (GarritanStudio0002), and then tried to go back to version 1.2. ".gpo" files made with newer versions can't be read by version 1.2! (Can't find "StudioLayout" it says.)
And after installing this newest version (0003), I tried to load a .gpo file that was created by the previous version (0002) and it won't load and doesn't give an error message. It comes up blank! Oops. Careful there, you could have some setup work down the drain.
Backup your ".gpo" files before proceeding if there's any chance you may want to go back!
The installer also seems to be not as "nice" as the version 1.2 installer. Version 1.2 installed itself in the same place you put GPO itself. Nice. This new installer just dumps itself into C:/Program Files without even asking. If it's not going to let you specify a path, I think it should install in the same place as GPO.
On the positive side, the interface is nice, and it's cool that you can work with GPO and JABB... Say, are those ever going to be integrated?