I thought you could undo the allen bolts and take the factory x-bars off pretty easily? I've been meaning to try it, but it'd be good to know I couldn't do it before I tried.
I have the Yakima low-riders w/ 78" bars and it works well, but I don't have an aversion to the factory rails. Mainly because I'm used to running add-on towers which stick-up higher and aren't the sexiest looking things themselves.