I think so.There's possibly some confusion here - or maybe it's just me who's confused.
The "vehicle specification" for the factory roof rack is indeed 154 LB.
Adding the FrontRunner rack does not change that (note the footnote at the end):
Unlike most roof racks, the Slimline II was designed and built specifically for off-road use. Manufactured with high density aluminum, the Front Runner Slimline II tray is rated to carry 300 kgs / 660 lbs and can withstand the stress of any adventure. *
The load support slats fit into a double walled aluminum extrusion channel on the side profiles and are secured via locking nuts. This patented design creates a joint support that is stronger than usual for a roof rack.
The Slimline II’s L-shaped rear and front slat design increases the strength of the entire rack, making the Slimline II the lightest and the strongest roof rack available.
(*the rack must always be loaded in accordance with the vehicle’s load rating specifications).
So... with or without the FrontRunner rack (or any rack, for that matter) the specified limit for loads on our roofs is the same - 154 LB.
Right?
This article mentions 400 lbs for the 200 series, but maybe that’s a different country? “Locked and Loaded” by Scott Brady - loading and lashing