There is something really nice about putting on a fresh-smelling helmet every weekend, rather than a crusty sweatbucket. It's comfortable enough to leave on for the whole ride to altitude, and provides some noise reduction. It's also quiet in freefall, though in certain positions a little wind gets around the visor - it does not seal completely as an Oxygn design does. This slight leakage has never caused a problem for me, and I wear contacts. It may also help keep the lens from fogging.
Peripheral vision is excellent.
I'm never aware of any obstruction in freefall. Like probably any full-face helmet, you do have to tilt your head a little to see your handles. The Z1 lens is thinner and probably less impact-resistant than the thick Oxygn lens, but mine has taken kicks without damage. I don't use an audible but I have tried a standard TimeOut in my helmet - it seemed a bit thick and was pressed against my ear. A thinner audible would probably be comfortable.