I am one of those DMs and I've thought before about trying to build a system like this. The main problem for me with the screen is that it is hard from my position to tell exactly what square any particular mini is in. It would be great for me if my laptop's view of the map showed where minis were and where they were moving to.

I agree that I wouldn't want new area of the map to be automatically revealed, but detecting where they were and giving me a one-click option to reveal X squares around the mini would definitely save me time at the time.

That being said, this screen is a non-starter for me because it is just too small. We use a 40+ inch screen and I'd love to go even bigger than that. Definitely not down to a (maybe) 23x13 square screen.