No experience with Arai's other than their price is well above my budget, and when I have tried them on their "fit" dosent seem to work with my noggin.
But I did just buy a Shoei RF-1100 and have logged about 400 miles in it this month (adding an additional 2,400 miles this weekend!) so far I love it. Quiet, comfortable, great airflow when I open all the vents, great seal when I close them.