i mounted a cattle panel to the west side of our milk parlor in hopes that i can grow some vine up it to help with shading.
as others have mentioned - i have seen these used for trellis and i have eaten the food that grew on them.
i also agree with R Scott - pH extremes would be the only reason to worry about leaching - at which point the plant in question is likely dead
cattle/stock panels are one of my favorite building materials around the farm - i say go for it!
http://www.cloud9farms.com/ - Southern Colorado - Zone 5 (-19*f) - 5300ft elevation - 12in rainfall plus irrigation rights
Dairy cows, "hair" sheep, Kune Kune pigs, chickens, guineas and turkeys