I've got a Garvin Industries Wilderness Rack. Like everything else it has it's ups and downs.
Pros:
-I can open both sunroofs (Although the rear wont slide all the way back)
-Good $. I got mine second-hand but
www.4by4connection.com sells the racks and accessories and I have never had a problem ordering from them
-I like the look of it better than the Safty Devices (Not really a pro, just an opinion!)
-Same height all the way across
-Great Load rate. You can load at least 400 lbs up on it (But I would not recommend driving like that from NC to AZ in the dead of winter towing a trailer)
Cons:
-It's hella tall. Not many places other than the desert where something that tall would be viable.
-Multiple piece construction. Good in that shipping is tons cheaper but bad in that you have spots that are suseptible to loosening
-I do get a bit of "shimmy" when hitting rocky trails at faster speeds.
Not meant to push you one way or another. Just give you my experience and information. Granted I would love a Hannibal myself, but that's after I win the lottery! Happy Hunting!