Re: External drives?
Not really - unless you're planning to video edit a 1080p holywood blockbuster, or finalising that nuclear reactor design in AUTOCAD while sitting in starbucks. Which I doubt. For 90% of users, what they do while portable will not be the same as the stuff they do at their desk.
For most, the most storage intensive stuff (while mobile) will be showing off family vids and photo's and watching/listening to a few (not all) of their media files while travelling, whereas Word and powerpoint stuff will barely register. So the Authors comments about iphoto and itunes are pertinent for the majority of users.
And if you're the minority who wants more while portable, why are you even looking at the Air? Surely a fully specced retina or Win box with conventional high capacity spinning media is more your thing?