FWIW, my daughter and I took the previous incarnation of the Randonee rack across the U.S. with no problems beyond loose mounting bolts. They're a bit off-center now, because we both went down and bent them a bit, but they carried everything just fine. I probably had 30-40 pounds on the rear. (Is your friend going to use front racks, too? Tubus Tara is very good.)
The newer version of the Randonnee rack in the last couple of years has a longer center post up from the lower rack mount before it branches out. I'm a little bit concerned with the change (longer moment arm, necessary structural rigidity, blah, blah, blah), but I haven't read or heard of any failures because of that theoretical weak point. I'd try to leave the kitchen sink at home if I were loading that one, but it should be good with a reasonable load.