The PDX1 Defender 1oz Slug looks nice. Problem is you are limited to a single projectile in a high stress situation. My jury is still out on it, and I will need to play with it to decide. Until then the standard PDX1 Disks/buck are my option.
Here is the PDX1 Defender slug being tested a few days ago at SHOT with Rob Pincus and Winchester
http://youtu.be/v1PCBOzgD8c