You guys will be okay, it’s going to reduce your unsprung weight a little and you won’t worry about any long term rust.I was thinking the same thing, but I'm sure they just make it thicker to withstand the needed forces.
I really like that it's aluminum. As Yoshoobaroo said, tons of high end performance cars have it. Reduces unsprung weight quite a bit which has many benefits (how noticeable it would be is probably minute). However, it's still part of the reason I went with the BRZ.
Not really. For people in snow or high salt environments it might be better long term.