I've found that what looks good in black and white is generally very contrasty. If I bake in a look in cam that 'I like' when shooting monochrome, it tends to end up with about 5 stops of dynamic range and zero latitude to adjust in post. I just stick to regular 4k uhd recording and turn on monochrome live view in the wrench C menu so I see approximately what I'm going to get with b&w.
No problem. I don't do much B&W work now, but back in my film days I did a ton. The majority of my work now is TV commercials. Try explaining to a client the concept of a shot being black and white in 2016. What the hey? If I'm paying for a commercial it's going to be full color. And while your at it, I don't like the black bars at the top and bottom of the screen. I'm paying for the full screen, and that's what I want to see.