As already discussed and answered here:
http://www.fsdreamteam.com/forum/index.php/topic,17311.msg121687.html#msg121687What you see doesn't have anything to do with GSX, and it's the very well know bug of P3D 4.1 (only, it doesn't happen in 4.0), which lose some textures when too many addons are installed using the add-on.xml method.
We have confirmation from LM this will be surely fixed in the next update.