In the 70's I painted a frame with rustoleum red primer and topped it with their enamel,two coats of each over a frame I had removed rust with a wire brush.
It's still there and doing well,but my opinion coverage is the main key to longevity. High points and sharp edges are hard to cover but if your good with a brush you can achieve the result you're after.
The thing that's different now with rusto paints is the dry time,making it harder to keep a wet edge. Back in the 70's dry time was at least a day, but now it's dry to touch in a few hours.
I tried to paint an I beam in the sun and that didn't work well cause the paint dried so fast it forced me to paint as fast as I could to keep a wet edge.
I think your choice is good and you'll be able to easily touch up any stone chips that take paint off or break it open.
Dan
