I've hit the old 975D (though it's been quite a few years back), and it's a fine driver. I think it's made of 6A4V titanium (6% aluminum, 4% vanadium). Nothing wrong with that, as I've never met anyone who's actually broken the titanium in one.
The Plus 10 has a Beta titanium face (which alloy, I have no idea), and I like the distance and forgiveness of it. The shaft is a Precision FM in stiff flex, and it even came from the factory with a Lamkin Crossline grip.
One of my playing partners laughed today when I told him it was a Northwestern club. He stopped laughing the first time I hit the ball. Sweet.
