Using cgx aga you get to use the Supergels and Superlayers feature of CybergraphX. (Make use of the CybergraphX commodity to edit settings) This helps the Solid window moving patch of mcp among many other things.
Speaking of which, I never understood why a 'system friendly' standalone SolidWindows and SolidwindowsMoving patch has never existed outside of mcp.
Edit: Playing with the different versions it seems the AGA Driver included in CGXv3 is tied to the Phase5 040/060 libraries, so the Aminet version is to be used on other configurations. Just ignore the included cyberbugfix is my opinion anyway