DevonDiver
N/A
As you know, but I'd just like to point out, the DMC counts against the student/Instructor ratio.
No it doesnt. Is this a typo? The Divemaster Candidate is not a certified and renewed Divemaster... therefore, not a certified assistant, as per the PADI definition.
In fact, there is no actual or formal designation of a Divemaster Candidate. They are a Rescue Diver (or whatever other higher qualification they hold).
The DMC is essentially interning and observing the Instructor's Open Water Class. It is not the DMC's class, and he is not paying to be there. Volunteering, yes.
Maybe it's different at your LDS... but everywhere I've been, people pay to take a Divemaster course. That makes them customers.
In this scenario, even if it is closed minded, non-progressive, and insecure, the Instructor has the right to ask the DMC ..or any of his students to change gear or configuration.
What right? Can you quote a PADI standard that gives an instructor that right?
I can quote several PADI standards that list exactly what the equipment requirements for DM training are. None of those standards prohibit BP&W configurations.
In fact, I even think it is debatable whether insistence on certain exact equipment set-ups could be considered a breach of PADI standards.

The DMC has the right to say, screw you, and to leave the pool area and head home. If the DMC has limited choices and opportunities to complete his DM training, he might just do as the Instructor asks. He should do the Instructor's bidding in front of new students. Confrontation is not an option until "Elvis has left the building." Then maybe the cannons come out!
Students/Customers also have the right to:
1. Contact PADI directly and seek a definitive answer about whether their gear is prohibited and/or unsuitable for DM training.
2. Complain publically or privately if their purchased training course does not meet their expectations due to personal or professional issues caused by the instructor.
3. Expect a full refund if they cannot complete their training course, because the instructor has imposed non-sanctified standards and/or imposes additional and unofficial requirements that cause additional expense to the student... or if the instructor refused to teach the student because the student could not, or would not, meet those unofficial standards.