Trek 7000, Trek T-900 Tandem, wife has a Navigator 300. We also have a '74 Schwinn Tandem we courted and got married on.
My Bike rack (only a 2 bike rack) holds our 66 lb. Schwinn Tandem and a 44 lb. Trek Tandem quite nicely...
You're weak point, if any, will be where it attaches to the car. Ours goes into the receiver hitch of my pickup, and flexes there a bit. Not knowing exactly what you have, I make this disclaimer- if it is one of those 'rubber bumper on the trunk lid and attached with velcro' types, all bets are off. But if it's bolted on securely, you should be fine.
You'll be OK until you drive through a ditch or over a hump too fast. The rack may permanently sag a little after such a bump, like mine did. Although the exact place where mine sagged is at a weakness in the design, not the tubing.
Bruce Gordon BLT, Cannondale parts bike, Ecodyne recumbent trike, Counterpoint Opus 2, miyata 1000
Of course there is a fudge factor built in. It is called the Safety Factor and can be anywhere from 1.5 to 5 times the posted load limit when human life is not involved.. It is NOT an excuse for you to be a little over the posted limit. For a bike rack it allows you to hit a reasonable number of pot holes without the rack failing within the warrenty period. Do not put 4 bikes on the rack and hit some rocky jeep trails in your 4-wheeler. I hope the Saris rack is steel and not Aluminum.