I don't want best case scenarios. I want responses based on what MAC can do for a business RIGHT NOW if I call in today in response to one of their ads and I want to become MAC certified.
Then you should have worded the question differently.

The answer to your new question is: Nothing.
Then the real question is : "Is the
potential benefit that MAC might offer my company worth the initial investment? And like any other investment it may pay off or you may have just flushed it all down the drain. To me, that decision can't be answered until they have fish.
Regardless of whether or not MAC ever actually produces a product to market, I have heard from several stores that are MAC certified, that the process of becoming certified (the record keeping) made their stores better from the beginning.
You are "assuming" that MAC is offering a better product based on all their strict criteria, and claims of net-caught, properly handled fish.
Today, nobody can guarantee those claims, any more than any other member of the chain of custody.
You and I both know we can get that with careful supply choices, no certification required.
I'm assuming that MAC will do everything they claim (hence the best case scenario disclaimer).
And you are right, nobody can make those claims and back them up currently. Which is why the proof (for me at least) while be in the fish, when and if they ever have any. A MAC certified distributor will be critiqued the same way we have always done. It's ludicrous to think that the vast majority of retailers are going to stop paying attention to the quality of their product, just because they come in boxes with stickers on them. If the quality is better than what I can already get, I would probably look into becoming certified myself so that I could then sell certified animals to my customers.
But not until I have actually seen the fish myself firsthand.
And yes, you can currently
do the same thing through careful supply choices. However, you can't tell me that improving all supply shouldn't be our ultimate goal. We both know that the entire industry can't survive on what the few "green guys" are offering. In order for the hobby/industry to improve we have to improve
all of the supply. The attitude of "as long as I know my fish are healthy" has got to end. Keeping a secret stash of clean fish and hoping that our competition is selling dirty fish isn't helping anyone. This industry should rely on knowledge and customer service, not secrets.

(speaking in gigantically broad terms here, so nothing personal was directed toward any person, organization, or company.)