This 2cy male Sylvia was observed near Eilat in southern Israel last week. It shows some contradictory characters for both mystacea and melanocephala.
In the attached link there are several images:
This bird stirred quite a discussion in Israeli forums, with no final solution yet. The birders who saw the bird in the field claimed that the images don't do justice to the bird. In the field they identified it as a Menetries's. However, images are images, and the camera captures what lies in front of the lens.
I am very interested in your ideas.
Yoav Perlman, Israel.