I have a BD half-dome and a Petzl Elios, and I've tried the Petzl Meteor III, Grivel Salamander, and the new BD Vector. I also own a nice expensive bicycle helmet (Selev Matrix) that is beyond comfy in its own rights. But hot damn, the Shield II just hugs so good.
So if you're just getting into outdoor climbing, or you need to replace your old, tired helmet, you must get a Shield II. There's really no other option - it's just that good. The suspension system hugs perfectly around your head and is snug enough to stay on without the straps done up, but will never cause you aches and pains.
Seriously don't take my word for it - go try one on in your local MEC. It'll cost you $81.36 CAD after taxes. For our friends in the USA, I do believe your only option to get the best fitting helmet on the market would be an adventure up into the Great White North - so come say hi!