I have a flip up, had one since BMW introduced them, which now is quite a few years ago. Got so used to them, couldn't use anything else, well wouldn't want to. I am naughty, never lock mine, as I think they aren't rated in anything but the locked position. I was in London despatching when the police were riding with theirs up, and pulling us for doing the same. There was a truce on it for a while, then they went back nicking people.
With regard to whats a good helmet & what isn't, check the SHARP ratings... http://sharp.direct.gov.uk/ Heres my AGV Stealth (2 years old) Here again with me wearing it @ Cadwell Park open pit lane track day, last year.