Ewest,
Not sure how to best answer your question about "too big". The largest pond one of our clients have added microbes to for over two years is 7 acres (treating the entire body of water). I was just at that pond a week ago and they are still using the microbes during the warm months.
However, some other clients have used microbes in only certain areas of larger lakes, too. I guess the question is subjective to a person's pond or lake management budget.
For the most part, we sell microbes because we have many clients who've asked for them specifically. I can't think of a time where we have "pushed" the use of microbes. We've suggested the use, but never recommended them as the only solution to the problem.
