[quotemsg=12060342,0,1106985]Even when paired with a keyboard, a 13" tablet would be pretty clumsy. My guess is most people would never use it undocked therefore a traditional notebook would be a better option. In my opinion this holds true for just about anything bigger than 10". Around 7-9" seems to be the idea form factor. [/quotemsg]
Folks, a letter-sized sheet of paper with 0.5" margins has a 12.5" diagonal; with 3/4" margins it's 11.8" diagonal. An A4-sized sheet of paper with 2 cm margins is 12.1" diagonal. I've always maintained that 12"-13" diagonal is the perfect size for a tablet. The 9.7"-10.1" tablets we've been living with so far are a concession to technology not yet being good enough to provide paper-like size at a reasonable weight and price.
7" diagonal with a 16:9 or 16:10 aspect ratio is pretty much a spot-on match for the text area of a paperback book. That's why that size tablet has been so successful. And 12"-13" diagonal is pretty much a spot-on match for the text area of a piece of paper (4:3 if letter-sized, 3:2 if A4). That's what it's going to take for tablets to truly replace the clipboard and paper. Remember, that's the ultimate competitor here -- not the iPad or Galaxy Tab, but paper. Once the technology is able to deliver it at a reasonable weight and price, I expect the 12"-13" tablets to completely take over and 10" tablets to become a distant memory.