I would think it would be a bit cumbersome to load the bikes on the roof considering the CX-9 is rather tall. Ever think of getting a hitch or if you already have one, getting a hitch rack? Its seems like that would be the easiest.
I was a bit concerned about that, and have done a few trials with the Thule Prologue I have now... It's not as easy as the 6 was, that's for sure. But it's not impossible either. Was thinking of keeping a step stool around too, lol.
As far as the hitch goes, that was my first thought. However, I don't have the hitch yet (but will eventually), and a good, wheel-on rack I'm looking at $400 bucks or so (can't do the hanging style, due to the geometry of my bike, the triangle is too compact. Tried LobsterClaws and adapters before too, but they didn't inspire confidence)...
So it was $100 bucks to get it on there now (got a deal on Amazon), or $500-600 bucks to get a hitch and a rack. In addition, as I've owned both hitch and roof racks before, the bike stays a bit cleaner and safer up on the roof. But then you get the negative of wind noise when the bike is up there. But you also know someone won't bonk it in a parking lot (or you won't bonk it, lol). But then you have to worry about low hanging structures.... AHHHG!
I really went back and forth on this. Trust me, I wanted to load up the back with a sweet Kuat rack with the built-in bike workstand, but coulnd't drop $450 on a rack. And with how muddy it is in CO right now (as you know @mxer), I didn't wanna keep loading the bike in the car. But, I figured I'd try the roof out and if it sucks I can either return or sell the thing (I got such a good deal on it I would probably break even locally on Craigslist

) I'll definitely report back if it sucks, lol.