I had a powder-coated Manik on my Tundra for about three years before it got some surface rust and I drive on the salt-laced streets of Michigan. I took it back when it started to rust and the place I got it from gave me a whole new one for free under warranty.
When I sold my Tundra last year for a T4R, I ended up with a WAAG largely based on rec's for other members. I'm happy with it because it is much more structureally sound than the Manik. I've had it less than a year so not sure about rust, but so far, so good.