I read several posts on a CTS forum last week but saw no examples mentioned of engine failures. It seems that the cam position sensor was overly sensitive and was tripping the check engine light too soon and cam chains were being needlessly replaced. The cam position sensor will be recalibrated to trip the CEL later. The cam chain elongation figure that I recall seeing was very small, about 2 mm. Oil change frequency will be increased to reduce cam chain wear. Our 3.6 has gone over 12,000 miles which may be too much.
I suspect that if you do not drive your engine frequently to extremes, you would never see a problem without the recall. This information is early and therefore subject to change. Here is a little more info. http://www.enclaveforum.net/index.php?topic=7662.0