I have had roughly 100pds on there and not a problem.
The other night I took my weights total of 200pds and it didn't budge. I however did not take it for a test drive.
If I had a secure load I would feel very comfortable driving with 200pds.
Keep in mind the bars wont bend with the roof rack sitting on it, the load is sitting on the bars of the roof rack and the frame of the rack sits on the outer edges of the cross bars. The all thread is added support, all this combined makes it very rigid.
Also the bars are sitting at 5/8" of the roof, I can stick my thumb under it.