I don't know whether Spike's kettle bottoms are 5 mm or 1 mm.
Bu when a modern SS kettle's bottom is advertized as 5 mm, that 5 mm isn't all SS. Instead, it's largely encapsulated aluminum (or possibly copper, in higher-end cookware). I don't think aluminum is all that much protection against denting...
And what the heck are you doing to your kettles anyway, that you worry so much about dents? I'm 65 years old, I've been cooking indoors and out for most of my life, and I've never dented a kettle bottom.
Yes, encapsulated bottoms supposedly spread heat more evenly, thereby reducing hot spots and burning. But are hot spots really a big issue in a brew kettle filled with swirling wort?
Of course, my original post had nothing to do with any of these technical points; I was simply dismayed by your bad manners. When a member spends serious change on something and is eagerly awaiting its arrival, it's bad form to tell him he bought a piece of junk. Even if happens to be true, which doesn't seem to be the case here....