I too have been playing with the idea of opening a curry house back in the states when I return. I believe it can be successful due to my observations here on Okinawa. Having a very large US presense here, whenever you go into a Curry House Coco Ichibanya, it is filled with Americans! I know there are a few Curry Houses in Southern California, but adding to the sentiments stated prior, they may be leaning too much to the Japanese tourist crowd in So Cal instead of the locals. Also, they seem to serve their curry on spaghetti instead of steamed rice?? As for the roux. I believe the roux is only the base for the sauce. Either at home or in a restaurant setting it will be how you "kick up" the sauce that will make it outstanding. The cooking sytle of the meats and vegetables along with "secret" additions such as carmelized apples, additional spices or golden raisins will truly add to the overall effect. Placement of the proposed restaurant in a major urbanized setting would help. Also, most Americans think "Indian" when they hear curry, so you would have to educate them on the profound differences. But as many Japanese are attracted to American cultural icons, the same is true with Americans in their interest in most things Japanese. This idea was recently boosted with the box office returns of "Lost in Translation" in the US.