steve,
yeah, the HTRZ-II is a completely different design. i don't own a set, but i've driven on them a few times (friend's car), and since i've owned a set of 712s, i can say that the HTRZ-II's offer much more grip, better steering response most importantly, they are confidence-inspiring.
i'm debating between these, a set of kumho ecsta MX or falken azenis for my next set of tires.
peter