My experience has been that the HD is significantly more aggressive than my 60's SS. This results in a much smoother shaving experience for me, regardless of the blade I use. Smooth as in both not tearing up my face and giving me a closer shave.
With the HD, I really feel the blade as it shaves and I hear that awesome pinging as the blade attacks my whiskers. I don't experience that nearly as much with the SS.
Of course, YMMV, and there are plenty of people here who are devoted to the SS though I think it would be hard to argue that the HD is more aggressive razor by a pretty fair margin. Of course, I could be completely wrong.
Merkur HD [I]Slant[/I]
AOS Pure Badger Brush
Nancy Boy Signature Cream