Yeah, I'm working on that body weight thing, see below.

But I know what you're saying and this all makes perfect sense, and yes, my bike is kind of heavy anyway. But I'm not talking about buying a titanium rack over an aluminum one to save 4 or 5 ounces. I'm talking about 5 freaking pounds. I also carry my bike up a flight of stairs, plus about a half flight at the bottom of those stairs. So if my bikes weighs a few ounces less, I probably won't notice, but 5 pounds? That's a huge difference. It's going to make a difference in the ride as well. 5 pounds less swinging around on the back when I'm standing on the pedals for a sprint/climb is going to be felt. It's going to make the commute more enjoyable irregardless of whether or not I'm any faster.