The only disadvantage of the Rocky Mounts is that the trays are painted, and when the metal under it oxidizes slightly, the paint flakes off. Yakima is definitely anodized so does not have this problem. Thule I think is also anodized but I don't know.
INNO (a Japanese based company,
www.rv-inno.com) offers a good round/rectangular compatible fork mount with locks included as well as the strongest rectangular bars I know of. They are anodized and my rack set (left outside on a Subaru for three years now) shows no signs of corrosion except the lock is stiff and the mounting bolts have some discoloration on them. Trays, feet, and bars are immaculate.
Personally, last year I owned a relatively new Yakima, an older Thule, and relatively new INNO rack. I sold the Yakima, am saving the Thule only for its feet and stretch kit (the trays I threw out), and use the INNO with the INNO fork mounts and a fantastic Thule tandem mount. When I mount the Thule feet on my short roofline car, I'll be using INNO bars and fork mount carriers.
I pay the same rate for any of the racks so that is not a factor.
I should point out that although I never worked for INNO, I did help them out on a volunteer basis. I worked their booth at Interbike for two years. They paid for my hotel room but I had to pay for food, a lot of gas (from San Diego), and my flight. They sponsor the Jelly Belly squad and I helped mount the team racks on their cars and SUV at the beginning of two different seasons. I would not have recommended them if I didn't think they deserved it.
cdr