Decided to give this a go, begun blocking out the shapes and trying to find the camera angle. It was quite difficult to get it to somewhat match the reference, for now it will work. Next up some rocks and more detailed pipes.
Only thing that uses some kind of lightmap in Cry Engine is the terrain. You can calculate a "sky accessibility texture" for it, which is basically an AO map.
Very cool! I'd say go with CryEngine for a scene with this much lighting. IMO, Cry's renderer is leaps and bounds ahead of UE3 in outdoor lighting conditions.