You would be mad to pay more for a faster machine with more functionality?
The only two advantages of significance that the Air has on the Pro are screen resolution and weight, and the former comes at the cost of color accuracy and a high incidence of artifacts like visible gradients and spotlighting. Battery life is actually in the Pro's favor, by 1 to 2 hours in controlled tests designed to emulate "common use" scenarios. I shouldn't need to cover things like ports, RAM and user upgrades.
add on to that the mbps durability, by that i mean the screen will not scratch easily because it has a glass panel covering it while the macbook air is subject to scratching