Grips seem to be a problematic thing for me. Grip size really depends on how the club is held in the hand. Once I settled on a comfortable way to grip the club, more with a bias towards holding it in the fingers, I settled on a standard .600 core grip on a .600 shaft but. Technically, a static hand measurement says that I should use a mid-size, but I found with mid-size grips the 'release' didn't feel so great. So I think I've finally figured out that a standard grip is best for me and my swing. Also, I like a corded Wrap grip, as the Wraps help me get slightly more of my fingers and hence more grip on the,er, grip.
Not crazy about the Dual Durometer grips. I don't like grips that will mute the response from the club head. But that's just me.