I know this is a late response, but I absolutely HATE my z-coils. The hospital that I worked at through nursing school a lot of the nurses had them, and I told myself that with my first real nursing paycheck I would buy some. So $230 later, I had myself some fancy z-coils. They felt pretty good at first, but really no better than a new pair of nike's.
6 months after I got them I couldn't wear them anymore. They make my knees, ankles and hips hurt so badly that I was almost in tears at the end of a shift (a definite problem for someone in their early 20's). So I took them back to the store and told them this, because supposedly you can get them adjusted whenever you want and it will help with comfort. The lady told me that they couldn't adjust the coil because I had bought the covered ones. So instead she gave me a shorter coil that didn't stand as high, and I tried those. A month later, again I had the same problems. At this point my feet hurt even THINKING about wearing them.
I'm really disappointed in the product, and am upset at myself for spending so much $$ (esp since new co-workers told me not to). Now I just wear $50 Nike's because I know they are somewhat comfortable, and I don't want to drop another couple hundred $ on shoes that hurt me. And for those that may be wondering if it was the place that sold them to me-I went to the original store in Albuquerque.
And if it tells you anything, Z-Coil did a study at my hospital a few years ago where nurses could sign up and get a free pair if they filled out periodic surveys and NONE of those nurses wear Z-coils now, even their free ones. They all discouraged me from getting them. Just my