you might have to I dont
the available battery meets my days worth of work requirements with
no need for me to carry a PSU. At most I'll have a notebook powered up for four or five hours during the day the remainder of the time Im carrying them around the sites Im visiting.
The storage space meets my requirements with 30 gig to spare, larger drive is just more spare space.
Likewise I average 25 to 35 percent CPU loading on its daily tasks, all the higher spec processors would offer is more idle time
Wether you consider both to be the same for hand carry, I dont. My response was based on what I know works for me and what Ive long found doesn't.
1 Kilo notebooks I've always been happy to hand carry all day
Heavier notebooks I find myself sticking in a backpack after a few days, then getting fed up with the hassle of lugging that around. Pretty soon after that I start leaving em sitting at home (relying on whatever the sites I'm visiting have got to offer instead).
Past experience tells me that for me personally the 13 MBA would go the same way.
As for Apples to Apples you might as well dig out a 17"MBP I'm sure by time you factored in an external monitor and a portable hard disk the 13" would start to get a bit bulky in comparison. And
it would still be slower.