I've got a friend that is using just 1515 extrusions for a machine in his shop for the past 5 years and he says it's still rock solid. As you can tell I went way way stiffer. Each double anchor has at least 1200 lbs pressure holding it together, and I'm using at least 2 at every joint. I think it'll be okay, but yeah, I'll be checking each joint like a madman the first few months.
Barry