We jumped right into the newly opened Aion Public Test Server and the XP increase compared to the regular client seems to be 30%. At least on the first levels. We’ll try and officially confirm this.
Also, when trying to create the copy of the PTS client we ran into some difficulties although we followed the instructions for manual installation. I have Aion installed in non default directory (D:\Aion2) and when I copied this directory into D:\ and renamed it (so the new directory is called D:\AionPTS), as the instructions suggested, the NCSoft launcher still didn’t recognize the PTS installation.
I created a folder named AionPTS in C:/Program Files/NCsoft/ and copied the files there. The launcher recognized it then and things went smooth from there on.
Also, I noticed in the official forum thread that people sometimes suggest you delete the addcache.xml file in your AionPTS folder and repair the client.