This has been posted before but, the reason the Ren roof bars aren't rated as high (weight limit wise) as the non Ren ones is that the Ren ones with the tupperware have the tupperware mounted to the roof rails with a funky clamp type arrangement so the weight limit is lowered as the clamps seem to be the weak link. If you remove the tupperware and use aftermarket cross bars/mounts there's no reason why the rails wouldn't hold just about anything you put up there (within reason of course).
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=1621&highlight=renegade+cross+bars
_________________
My pics!!'03 Rennie w/all Tupperware
Custom Roof Basket
Mopar Tubular Brush Guard
Garmin GPS V & Laptop w/Nav software
RAM products laptop mount
Maglite w/mount
Rear cargo bay tool cabinet
AllJs Rear Shelf
Rear receiver
250k miles!
LOST #CR051230