Updated models with AMD graphics options expected in early 2017.
Apple Releases Second OS X 10.11.2 El Capitan Beta to Public Beta Testers
The second OS X 10.11.2 beta is available through the Software Update mechanism in the Mac App Store to those who are enrolled in Apple's beta testing program. Those wishing to join the program can sign up on Apple's beta testing website.
The first OS X 10.11.2 beta did not include any outward-facing changes, but it likely includes bug fixes, security enhancements, and performance improvements to address issues discovered since the release of OS X 10.11.1. Apple's release notes for the initial developer beta asked testers to focus on Graphics, Wi-Fi, Calendar, USB, Notes, Photos, and Spotlight.