Lake Hickory Scuba & Marina is a full service Scuba Center that offers classes through PDIC, SEI, CMAS, and even PADI. We are currently working on becoming and SDI, TDI, and ERDI facility as well. The reason(s) we offer so many training agencies to our customers is because we believe there is not just one agency that fits every divers' needs. For instance, divers who want to push themselves harder and learn more skills that can better prepare them for emergencies can choose to take an SEI or PDIC course. For the versatility and convenience of self study (or even the convenience of time) and online capabilities, then PADI would be a great option for them. To be able to introduce the love of scuba to 10 year olds then PADI would be the route, where PDIC and SEI / CMAS require they be older to start training.
Direct competition and location is another reason we decide to teach for multiple agencies. In an area that has 5 PADI shops all within 20 miles of each other; those shops will usually all be comparably priced. Now if one of those shops were to teach for a different agency, say one that does not charge as much for training materials as say PADI does, then they can lower the price for training and potentially obtain and retain a larger customer base. The practicality and financial benefit to teach for multiple agencies is different for each shop. I would suggest sitting down with your business partner and decide if the inflow of profit is still substantial enough to pay for renewal fees each year on the Instructors and the shop fees if the shop is an affiliate. With the current trend that PADI is showing, I believe you will start to see more and more independent Instructors jumping agencies and even your smaller PADI stores jumping over simply to get cheaper fees.
Now with all that being said, sticking with one agency will sometimes be better, because having to many choices for the students will tend to confuse them, and then you are competing against yourself when attempting to sale courses. Students will want to know why you push one way or the other for different agencies. If you state well I make more money if you take this one, then they may get a bad taste in their mouth because they see it as a money maker for you.
Here are the typical classes that I try to lean students towards (based off my personal philosophies towards training).
Open Water - PDIC or SEI
Advanced Open Water - PDIC
Rescue - PADI or PDIC
Specialties - PADI or PDIC
Dive Master - PDIC or SEI
Assistant Instructor - PADI
Instructor - PDIC or SEI
PSD / UCI - PDIC
As you can see each agency has there pro's and con's. Food for thought, hopes this helps.