Interesting, I keep thinking I'll build something like this, although I note that Seiki discontinued their big 4K screen. The key for me in previous "smart boards" has always been that drawing on them has been like drawing on a tablet, which is to say the "ink" is way behind the pen when it comes to updating the display. It is the same experience on a slow timeshare system where you're typing doesn't get echoed for a dozen or more characters. And when composing text, you at least have a moderately easy way to back up and correct but when drawing not so much. That and the occasional sample glitch that suddenly has the pen making a mark 2 miles off screen you get this weird across the screen line.
