It's useful to identify what those changes are and list them out. To the extent that shaders need to be updated, we need to know which parts broke so we can fix them without starting over from scratch. It's useful to submit it as a bug, even if the only result is that we find out it is deliberate.

GlossyBSDF seems like a deliberate one. On the other hand, the non-cycles version of Glossy was a bug.