Carnuba's only last a short while, few weeks at the most. While polymer's can last up to a couple of months.
This stuff works very well -
http://www.topoftheline.com/16ozmaxpains.html
At our shop we do some detailing, trying to stray away from it now due to the time involved. We mostly use 3M & Hi Temp products and many others not available in the store.