As a non-grandfather who regularly wears a fedora, I can tell you that if you wear it while thinking you look like a dork, you will look like a dork. (Also if you wear it with a button-down or T-shirt and jeans.)

If you can wear it long enough to get past that and start wearing it unselfconsciously, the practical benefits you already noted in the OP are real. Also, it gives you incentive to dress more grown-up-like. If you stick with it for a while and still feel like everyone is looking at you as a debonair sysadmin, then, well, at least you tried.

For the same reason, +1 on starting with a "stingy" brimmed hat, though going more Stetson sure keeps off the rain a lot better.

/gkk