OSX 10.11.x and Adobe CS6 suite incl photoshop?
Last night I updated to OSX 10.11.6. I have made no changes to my Photoshop CS6 installation since posting this question.

With this update, Photoshop now opens and loads perfectly fine. I have not done any complex operations, but it works fine. Seems the Apple Feedback site may get read after all.

This may be of interest to other Mac Users with issues with Photoshop CS6.