It looks to me like the OEM rack for the current models might actually be a Yakima rack. The DOT limits all car-top racks to a maximum capacity of 165 lbs, and all the crossbars by both Thule and Yakima can handle that weight and more. The real weight limit is the attachment points on the car, which for these cars, I would hope is the full 165 lbs.
I had aluminum Thule crossbars bend with just a single kayak on the roof, so don't be so sure. It's pretty common for aluminum bars to bend, I have yet to see the round, steel Yakimas fail for anything but garage run ins.
I'd be inclined to try to stay a good bit under the quoted 165 limit on our cars, as the mounting points might be nice and burly, but the surrounding metal that the feet sit on doesn't seem all that thick. I've seen many, many cars damaged where the feet sit when the roof's been overloaded, and while the rack will stay put with 165# on it, it might cause minor cosmetic damage to the surrounding areas. Worth noting that one reason I bought the 3 over a Honda Fit is that the new Fit's roof is too thin to support a rack at all, Yakima and Thule don't support it for roof racks.
Worth pointing out the impact of speed on roof force too. A static 165# roofbox, bikes, kayaks, etc might be well within limits, but run them up to 80+ mph and you're certainly pushing your luck. But as an aside, I used to worry about transporting my bikes at speeds over 80 mph, until I spent a few years in Germany and frequently saw folks with bikes on the roof at speeds up to 250kph, or 155mph. I stopped worrying about it after that.