I find it strange that they use a straight count of students that pass their IDC as a success measure for the rating. It seems obvious that a combination of straight count and succees rate (number of students achieving divided by number of students attempting) would be a better measure.
Given that a truly valid rating does not exist, what is the best way to choose a place to take the IDC?
I plan to take it in about a year, and my goal is to become a good instuctor, not to just get the card. So far I have found no clear and reliable way to choose where to do it.
I haven't spent much time in the middle of IDC's, but I suspect the success rate is pretty high. The Divemaster course is where the real work is, and where a student finds out whether or not they have the skills to handle being an instructor. Since the DM course is a pre-req to the IDC, anyone not able to handle the IDC wouldn't make it to the course to begin with.
And considering the cost of taking the IDC... anyone taking the course is all the more motivated to succeed.
Bruno, if you're planning to go pro, focus on finding a good instructor for your DM course. It's much more important, in terms of learning what you'll need to know and do as an instructor, than the IDC. It's difficult to know who the right instructor is when you have limited experience dealing with instructors, but go with your instincts. You'll be spending a lot of time with your DM instructor in a "mentoring" role: they'll provide you with a lot of good advice and put you to work helping them with classes. So make sure it's someone you can work with comfortably.