Was wondering if you could rum Environment X along with FScene4X ?
I don't have either, but the way i see it is that FScene4X is just textures for the ground and then Environment X is just textures for the water and sky, so i would say yes, but if Environment X does have ground textures also then they will overrwrite the FScene4X ones if installed on top of them.
I swear, there are just way to many ground replacement sets, LOL.