I have an older Arai RX7-RR4 which I love. Great shield venting, not too noisy under 90mph and I can personally vouch for its safety. The newer Arai RX7's are supposed to be even better. I also have a Shoei RF1000 which is even quieter but I have'nt had it in the rain and haven't used a Shoei the hard way yet.
http://www.powersportequipment.com/s...1000_joust.asp
http://www.powersportequipment.com/a...lid_helmet.asp
Don't let the price scare you, they're worth it.