Ed, I'm not what you'd call impartial so I'd wanted to sit this one out. But since you're not getting what you're looking for, I'm adding my 2¢.
I have dived with both OE East and The Dive Bus. I think which one I enjoyed most is not as relevant to this discussion as my impression of the manner in which their businesses operate (but my analysis probably will leave little doubt as to my preference).
OE is a large operation. Most of their customers are a "captive audience", guests at one of the resorts for which they serve as house dive shop (which is not, of itself, a bad thing). They have many dive boats, many divemasters, and many, many customers. You will have lots of companions if you go out on one of their dive boats.
They are what I call your standard "taxi" dive service. The give you a bottle of gas, take you somewhere, let you dive, and bring you back. They have a regular schedule of dive sites that they keep to, week in and week out, rain or shine. When I've dived with them their divemasters always were professional in their behavior, if somewhat staid.
OE does what it does very well. They have a very nice dive shop. Their boats and equipment all appear relatively new and well maintained. They have many, many satisfied customers.
The Dive Bus is a small operation. Their business is based on customer service. They don't have a built-in clientele; their customers have to actively seek them out.
The group you'll be diving with will be so small that by the end of the day you probably will know the given names of all your companions. Regardless of who your divemaster is (and presuming it isn't Mark himself), he was hand-picked by Mark and Suzy as a fit for their customer service philosophy. And he's only one layer of management removed from the owners.
In fact, the owners take a personal interest in every diver who walks through their door. In their business plan, your enjoyment of the experience with them above the water is just as important -- if not more so -- as you experience under the water. After all, every dive shop on the island dives in the same ocean; they all have access to the same reefs and the same fish. The Dive Bus's best opportunity to distinguish itself -- and, in the doing, attract those discretionary customers -- is to provide a level of personalized service unequaled by their competition.
You can peruse the threads mentioning The Dive Bus and judge for yourself how successful their efforts are.
But I wouldn't get too wrapped around the axle over this. I have little doubt but what you'll have a great time diving with either.
