We are currently running XE SP 23 i1, on V5R3. Here is some of the issues we have had. Any fat client that you don't also upgrade to V5r3 will sporadically get odbc database retry issues. You know, you'll get the box for re-entering the jde/password. Upgrading the fat client client access will immediately fix this. Second, I had some issues with promoting WF. The solution to this was actually upgrading my local client access to higher than the as/400. I had to upgrade to service level SI16496.