The Boox Tab X C wants to be your eReader, notebook, and laptop all at once — but it's not quite pulling it off. At this point, I think I may just be AppleInsider's resident Boox expert. I've reviewed a lot of Boox's lineup, from the tiny little Palma to the Note Air 3 and everything in between. And I really appreciate what Boox is trying to do. As a person who routinely gives herself migraines from staring at her computer too long, I understand the allure of an ePaper display. And I think Boox seems to know that. While many of its devices are designed to be more capable eReader replacements, several in its lineup are trying to be productivity tools in their own right. Enter the Boox Tab X C , a massive 13.3-inch color ePaper tablet that boasts a stylus and keyboard support to Onyx's growing lineup. It's a bold attempt at making eInk more than just a reading tool, though it might be trying to do too much.…