Updated models with AMD graphics options expected in early 2017.
Apple Releases Third OS X 10.11.4 El Capitan Beta to Public Beta Testers
The third beta is available through the Software Update mechanism in the Mac App Store for 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.
OS X 10.11.4 appears to focus largely on under-the-hood bug fixes, security enhancements, and performance optimizations with few noticeable outward-facing changes. OS X 10.11.4 offers password protected notes in the Notes app, an import function for importing Evernote notes into the Notes app, and it includes Live Photos support for the Messages app.
Apple is likely to release OS X 10.11.4 in the spring, alongside iOS 9.3, watchOS 2.2, and tvOS 9.2.