I use Nissan roof rack cross bars on my MO to support my ski box. I like them fine and does not detrack from tthe MO look. The only problem that I have is that they seem to whistle at hwy speeds, but when I close the moon roof cover I cannot hear it. I do not leave the cross bars on all year long, but only when I need the ski box on.
I use Thule cross bars. They were originally on a Jetta so the bars are just barely long enough to reach from one rail to the other through the clamps and the endcaps (perfect fit IMO). I never liked the huge overhang that aftermarket cross bars give you.
They take only 10 minutes to put on or take off. So, I only have them on when I'm carrying something up there.
I just don't get it. What's the point of having rails without crossbars? Why would you take them off? The only reason I could see is if it was causing a whistle.
Actually, that's another one of my gripes about the packaging options on the MO. You should be able to add the rails/crossbars to a base MO, not require the Priemium package. And the crossbars should be included any time the rails are included.