All you say is true, but I have both (iPad and 11" mba) and have been going with the MBA more and more. I found I mostly used the iPad for movies on flights, but I can do that with the MBA even easier (no need for iTunes to copy movies over).

I have a picture I sent to a friend with the iPad on top of the MBA, both closed and the MBA isn't *that* much bigger, although yes, you have to open it up to work. But for size in the bag, not a big difference. I have yet to pull it out for TSA, I just toss my bag on the belt and they have never pulled it out, domestically or internationally. I think it's the same story with the iPad.

I can tether wired to my iPhone and I get >4mbit connection around here with the iPhone 4 and the newer AT&T network in some of the major cities (like here in SF). When traveling internationally I can get unlimited iPhone data on our FAN account and tether with that too (shhh...)

I get a real keyboard. I have the Apple bluetooth keyboard for the iPad and it's great, but if I'm taking that and the iPad, I'd rather just take the MBA.

Real applications like MS Office for work, great email, I can write real documents and presentations, save them to USB, manipulate them as needed, etc.

One sticking point you mentioned and is a sore spot with me is battery life. The iPad is awesome, the thing is indeed just a big battery with a screen on top. The only time I'm getting 4+ hours out of the MBA battery is when I'm just doing email on the plane, nothing else. I find that videos, depending on the codec they use, will either sip the battery, or drain it like crazy. I'm not wise enough enough to understand which codecs use more CPU and thus battery, but that is my experience.

For extended battery life, on the MBA I've been using a Woot purchased 18000maH Energizer battery (was about $100) and I can go coast-to-coast twice without charging it and run my MBA the entire time. Sucks to have to bring an extra battery, but it has about 5x the capacity of the built-in MBA battery. Just did a SFO-CUN-SFO trip, using the MBA the whole time and I have about 40% battery left. Battery is good for 500 charge cycles.

I know lots of you guys are great at typing on the iPad, my hat is off to you, I'm too inept to do it well, I don't know if I type too fast (~80 wpm) and I tend to write volumes for work email or maybe I drag my wrists when I type, but I could never get a rhythm for it. Maybe it just takes commitment and I'm too happy using the MBA to do it.

I do love using the iPad's Kindle app for reading in bed at night, nothing really compares to that.