I got that middle one - is it a Dragonfly 2? -- ahead of a beach trip earlier this summer. Wore it for a week in the surf and in saltwater pools, and not a sign of rust. I was really impressed.
However a couple weeks ago I had it on and tried to get something out of my pocket while sitting, and the damn thing came open enough to drive the tip about 3/8" up and under the skin on my pinky middle knuckle. OUCH. I'm kind of snakebit by it now...