We have a member, FLWrd, who uses GPO4 Aria with Logic having problems with held notes. His post is in the Support and Technical forum:
I have answered the best I can but I use Sonar. It would be good if fellow Logic users could call in and reassure FLWrd that GPO4 Aria works fine in Logic.
Once we have confirmed that Logic works fine with GPO4 we can then move on to make other suggestions.
Logic users, please call by even if just to post that Logic/GPO 4 works well.