I have three....1/2, 3/4 and full face. I wear(and prefer) my 1/2 80 percent of the time and go to the 3/4 and FF as it gets colder. On long trips I take the full face in case of rain. A 1/2 helmet suks in the rain.
I have an Arai corsair (fullface) for winter and a Schubert J1 (3/4) for hotter season.
The Shubert is one hell of a helmet: it gives you the comfort of a 3/4 with almost the same safety of a full face thanks to the chin guard hoop. Google it and you'll find some interesting compares...
if you want to see it: http://www.schuberth.com/index.php?id=22&L=1