It’s nice that we can share our cooking experiences here. I also had trouble with cooking the roux sauce. From my own experience, I noticed that the smoothness of the sauce depends on how long I cook it and on how good I whisk it. By the way, I’ve found an article about the best whisks for cooking and an interesting fact is that it’s important to choose the whisk according to what you are cooking, as there are a lot of different kinds of whisks. Maybe, you just don’t use the right whisk and that’s why the sauce is not as smooth as you want.