Exactly, Gadgetfreak. We are in agreement. Especially the point about having an extra bag as a day bag.
I also once (1.0!) carried a bag that was probably 16kg (photo gear plus laptop) and it was baaaad. Never again.
OT:
Allow me the question, on that trip you are talking about, why did you even take the Ipad if you already had an MBA with you? Was it just creature comfort because the Ipad is such a nice tool for surfing or can the Ipad do something the MBA cannot? I wondered myself whether I should get an Ipad or an MBA. The decision was for the MBA once it has a Retina display. It weighs as much as an Ipad with case and keyboard. So no real weight difference there. But it has better connectivity, more memory, more power and a full file system. I hope they bring one out soon that does have the Retina display.
Till