I have an Aura HD now. To go for a 7.8" reader I'd need the following:
- Flexible substrate for the screen. A glass substrate that size would be too fragile.
- Resolution (dpi) no worse than the Aura HD
- Battery life no worse than the Aura HD
- Minimal weight increase over the Aura HD -- assuming that the weight is fairly evenly distributed across the entire device. If they use the old Rocket Ebook reader's trick of putting pretty much the entire battery in a bump that goes right in your hand, the weight could go up a fair bit.
Those are my reservations. Satisfy them and I'll run right out to buy one. Fail to satisfy them and I'll stick with my Aura HD for another generation.