Just my opinion (and I only began diving this past summer) but I think that an instructor forum should be open. I can see how there might some things that instructors should not give out or say in public (especially criticisim of students with identifying information), but in generally I feel that the greater good would come from open discussions. Some of my reasoning is based on who would someone new to scuba evaluate the different agencies? Reading instructor comments and thoughtful discussions may help someone make an informed decision and perhaps save their life. Also, students evaluate instructors as well. While I may feel able to ask for my money back if I found the instructor's performance inadequate, someone else may not without first having some insight as to what should be expected.
Overall, I cannot see that much of the posting on the proposed forum would actually require privacy. If an instructor needs to vent about a student either save it for somewhere else or do it in a constructive, non-identifying manner so others can learn from it.
I would definitely support having some form of identifier for diving professionals. It is still I choice as a non-professional diver whether to listen to that person or not, but it would give some indication as to sert level. Perhaps also include an indicator of number of dives, although that could never really be verified.
This is too long of a post for me. Basically, I come here to be exposed to many different ideas and experiences. Some times I ask my instructor questions based on what I find here, which wouldn't happen if I couldn't read it.
Also, instructors may have an impact on training standards, but something tells my that students money will have a bigger impact. As an OW diver I have quite a few more opportunities to spend more money on training and I am much better informed now than when I was looking for my initial training.
S