Agustin, I've been playing around this weekend, trying to bring a node of the city in Adamantus into Unity. I know that you're working on Asylum, but I encountered a problem with adding water to a scene, which I thought you might want to know about. I don't think that you have much water to animate in Asylum, so you may not have encountered this yet.
For the node, I have a transparency map for both the sky and the canal water. I apply the alpha maps to the textures of the node and I can see that the sky will work, but the water shaders (at least the basic ones) are designed to display on a horizontal plane. The plane works if the cutout is in the bottom cube face, but if the water plane is rotated 90 degrees to fit on a side of the cube, the texture is stretched vertically. I also tried using a half-cube and a hemisphere for the water, but there's the same issue as the texture stetches up the sides. This may just need a better or custom shader, which is beyond my abilities thus far, but I wanted you to know about the "problem."
I also had a problem with the seams showing up if a "real" directional light was added to the scene. You've obviously worked that out already, though.
P.S. - I also had to add the alpha into the diffuse textures, because I could not find any way to add them separately. Again, I'm guessing that you've written a custom shader to take care of this.