I have an NTSC Monitor II (A2M2010), and I was curious if it could be safely used with European systems (Apple II or otherwise). Since color is not an issue, I was primarily concerned about how it would handle the increased resolution and lower refresh rate. I would just plug a PAL device into it, but I'm not well-enough versed on the subject to be sure that it wouldn't be damaged.
Yes it will work in monochrome.
It will not damage it. It may or may not have vertical hold and size issues, though.