The Local IAEI has had a lot of conversations about rods too. The consensus is all of them rot out pretty quick down here. I was really surprised that anyone would even consider galvanized.
I know right after I moved in here I was fixing a piece of 12ga Romex going out to the dryer in the garage and I buried THWN/EMT. About 2-3 years later I had cause to dig it up. The EMT was just a rusty trail in the sand with little chunks of rusty metal in it.
Right now our defacto ground electrode is a ufer.
