Thule Hull-a-port
 

Has anyone used these to transport an outback? If so did you ever travel with it on the rooftop how did they perform opposed to laying the kayak flat?

Joe, in my experience the Thule hullaports are the best J style racks out there because of the contact area where the kayak rests. Even though they worked great, they still aren't as stable as laying the kayak flat. I always used bow and stern straps to further stabilize the kayak for freeway speeds. Just make sure you position your kayak in the J cradles in the most stable angle. I also like the design where you can fold the rack down when not in use. I've used up to four sets on top of my rack and folding makes the loading process easier as you can fold the racks out of the way and maneuver 4 kayaks to fit. Hope this helps.

Big selling point for the Hullaport is that it allows you to get 2 kayaks on a load bar that won't accommodate 2 otherwise

BTW the Hullaport Pro is the one that folds down allowing you to go into parking garages or your own garage without taking the component off, just fold it down when not in use.