It would be useful if there is a note in the manual that when using the airframe specific config, the main/built-in gsx.cfg should be removed for it not to be used instead of the specific config.
That's not how's supposed to work. By design, the specific config will have an higher priority over the generic one. I just re-checked it now, and it works as it should.
What you must keep in mind, is the location of the airplane customization file matters more than the generic/specific config. Which means, if you have an airframe-specific CFG file in the Airplane own folder, and a generic CFG in the %APPDATA% folder, the one in %APPDATA% will ALWAYS take precedence, even if it's "generic", and this if of course correct because, if it wasn't like that, you would lose the ability to customize an airplane that came with an airframe-specific config from the developer.
The airplane own folder should only be used by developers to supply a GSX configuration, but everything YOU do, should always be placed in the %APPDATA% folder ( as for my previous instructions ), because everything located there will always get the highest priority, regardless if it's specific or generic and, of course, *within* the same location, the specific will get higher priority of the generic so, consider the following situations:
1)
GSX.CFG in P3D\Simobjects\Airplanes
GSX-F-WWBA.CFG in P3D\Simobjects\Airplanes
NO folder for that airplane in %APPDATA%\Virtuali\Airplanes
GSX will use GSX-F-WWBA.CFG, if you select that variation, because the airframe config takes precedence over the generic config, and there's *nothing* in %APPDATA%
2)
GSX.CFG in P3D\Simobjects\Airplanes
GSX-F-WWBA.CFG in P3D\Simobjects\Airplanes
GSX.CFG in %APPDATA%\Virtuali\Airplanes
GSX will use GSX.CFG, EVEN if you select the F-WWBA variation, because anything in %APPDATA% will take precedence over any file in Simobjects\Airplanes.
3)
GSX.CFG in P3D\Simobjects\Airplanes
GSX-F-WWBA.CFG P3D\Simobjects\Airplanes
GSX.CFG in %APPDATA%\Virtuali\Airplanes
GSX-F-WWBA.CFG in %APPDATA%\Virtuali\Airplanes
GSX will use GSX-F-WWBA.CFG, if you select that variation, because the airframe config takes precedence over the generic config, since they are both in the highest-priority folder.