I play in 1366x768 on my laptop, for example.
Gah, I have tried every single resolution my monitor supports trying to get MCO to run at 1366x768, but it always ends up at 1024x768. I've gotten it to work on every other resolution it supports from 640x480 to 1080p.
I'm playing on a 48 inch 1080p LCD about 6 feet away, so at resolutions greater then 1024x768 unit names (as well as parts of the mechlab) become alomst impossible to read. I can do it but it's right on the edge of my vision. If I get the names on just the right background I can usually make out what it says, but I'll end up with a headache.
I played with the config files until I figured out the resolution command wasn't being used in v156. I tried every compatibility mode and every option therein but no joy. So I just live at 1024x768 stretched, which I don't really mind all that much. Still sad though, as I know how much better the game looks at those higher resolutions, it's just not worth the cost in my case.