Jar'd roux is fine, but I just prefer to make mine. I prefer to cook it to the desired color for the dish I am making. It really doesn't take very long if you know what you are doing, and I just enjoy the process.
I have no problem with jarred roux. However, when I cook, I want to control the color of the roux, depending on what I am cooking. For that reason, jarred roux, for most part, doesn't work for me. It may be perfect for those who lack the skills or heart to make their own, but I will continue to make mine.
Agree, I make a roux for lots of things. For those I make my own. In a pinch , for a gumbo there is not a damn thing wrong with cheating a little