I don't know how I feel about carry around a 12" or 13" iPad (a 13" version is widely being reported as something Apple is looking hard at). I suppose I will learn to like it. I'm sure it'll be light enough and capable of doing more in terms of productivity than today's 9.7" iPad or the iPad mini. And if that's the case, I'm probably for it and may even buy one.
Right now, I'm on the 11.6" Macbook Air as I write this post. A 12" or 13" iPad would have a slightly bigger screen, not to mention that it'll probably have a Retina Display that even late-2010 Air and the current models does not support.
I'm talking about this now for a couple of reasons. More at On Apple.