It's much simpler and more convenient to use one device than two, which is why people no longer use Palm PDAs. This doesn't mean Surface Pro is the best form factor for everyone. Surface Pro has about the same battery life as a MacBook Air, but it could be much longer if the keyboard had a second battery.
That was the idea behind the Asus Transformer, and in hardware terms, it works very well. (The software is another story.)
Of course, the resulting weight would be more like carrying both an MBA and an iPad as well, but at least you wouldn't have to pay for two motherboards, two screens, two keyboards, two sets of RAM etc.
In passing, you don't get longer battery life if you use two devices at the same time, as in your example. And if you search on one screen while coding on the other, the Surface Pro is dramatically better. You get real multi-tasking and two apps side by side on the tablet screen, and you can copy and paste between the tablet and the desktop, or use a Share charm to send stuff from one app to another. Basically, you're using the iPad mini like a book, aren't you?
That was the idea behind the Asus Transformer, and in hardware terms, it works very well. (The software is another story.)
Of course, the resulting weight would be more like carrying both an MBA and an iPad as well, but at least you wouldn't have to pay for two motherboards, two screens, two keyboards, two sets of RAM etc.
In passing, you don't get longer battery life if you use two devices at the same time, as in your example. And if you search on one screen while coding on the other, the Surface Pro is dramatically better. You get real multi-tasking and two apps side by side on the tablet screen, and you can copy and paste between the tablet and the desktop, or use a Share charm to send stuff from one app to another. Basically, you're using the iPad mini like a book, aren't you?