I was having trouble with this with my Rainy Afternoon, and solved it by creating a tileable picture in Photoshop using Flaming Pear plugin Tesselation to wrap the pic along the top and sides and then saved the image as a grayscale bumpmap at 256x256 size. Then I just imported the image into the Terrain editor and viola. A tileable terrain. Was alot faster and created the same effect with the same results you are talking about. However, I'm sure that your method took alot out of you once you finally figured it out! Good job! I would have never thought of doing that myself.