Strikes me that there's a very good reason for the size and for why it's a format which will sell (eventually). A 14.1" diagonal will display both A4 and Letter page sizes with virtually no scaling at all. Existing documents created for those page sizes will be visible at original size. A smaller screen would require either resizing, which could be a problem for small text, or reflowing, which even when it works perfectly results in layout changes which may be suboptimal. Small text is a potential problem for the target market - this looks to be aimed at business rather than students, in which case small text will be a turn-off for many older buyers. This looks like the right solution to displaying the vast majority of material that would otherwise be printed, eg print-ready PDFs. Two screens means, if the software is up to it, that you can "hold" one page on one side and directly compare it with another from an alternative document. A single screen just doesn't cut it for that. And in terms of portability, unless they whack on enormous bezels round the screens, this is the size of an A4 textbook, it'll even fit the bag you're currently using for transporting materials to and from office (or school) and home.
Now all they need to do is start using lightweight flexible screens, slot a couple more in so you can flip back and forward between several different pages rather than just see two, and they've got a winner. If it's cheaper. Till then it's likely a slow burn.