I did very much like my BlueAnt Z9i, but was off and on getting complaints about static and being able to be heard. I would at time have problems hearing people also. Not all the time, but it was annoying. The noise isolation would make it even worse when activated. I had some of the same issues wth my old Z9. Just dosen't seem to work well with my Tilt for some reason. Just dosen't seem to work consistantly.
I finally broke down and ordered the Jawbone 2, and it has been fantastic. I nolonger get complaints from the person on the person on the end.
If the Z9i works well with you phone, it a great choice. It has plenty of features and is very good volume not to mention you can save a little money over the Jawbone.
The Jawbone is a little more money, but in my case worth every penny. If you shop around you can get it at a good price. Got mine for $85 shipped off ebay.
Buttom line if they are both excellent, if one dosen't work for you go with the other. For me that turns out to be th Jawbone2.