OOOH.. How about TWO versions of each User Title... a 'plain' version for those who use open circuit, and a 'silent' version for those who use a rebreather..

I.E.

Photographer, Silent Photography
Divemaster, Silent Divemaster
Instructor, Silent Instructor
Wreck Diver, Silent Wreck Diver
Crazy Wreck Penetrating Diver, Silent Crazy Wreck Penetrating Diver
Crazy Cave Diver, Silent Crazy Cave Diver

(ps... I AM a Cave diver (intro certified at least for now, ...) and just because of that, many people would consider me crazy... But they just don't know what they are missing