I have the HTR Z on my 930 and the HTR Z II on my 911. I wanted the Z II on the 930 but they didn't make them in that size so I thought I'd try the HTR Z. These are new to me and only have one season on them. But from my experience with my HTRZ II tires they have been great.
First off you can't beat the price. Secondly they are very responsive and have great grip. Thirdly, again only street use, got just about 35000 miles out of this set of the HTR Z II. I probably would have gotten more but last fall before I put the car away for the winter I picked up a nail that is too far over to repair. So this spring I'll be buying another rear set, fronts are still good.
Another thing, I've taken both cars on long trips and I didn't find them noisy on the stock 930 and the 911 drowns out the sound of the radio, tires, passenger so I don't know if they are noisy or not.