I view these "mega clinics" kind of like Winston Churchill viewed democracy. The bad news is that they are cumbersome, complicated, and expensive. But in terms of a certain kind of impact, they're the best tool ever developed. Here are a few key quotations from Ellen White to consider:
"The work in the cities is the essential work for this time and is now to be taken hold of in faith. When the cities are worked as God would have them, the result will be the setting in operation of a mighty movement such as we have not yet witnessed." —Manuscript 15, 1910
"Henceforth medical missionary work is to be carried forward with an earnestness with which it has never yet been carried. This work is the door through which the truth is to find entrance to the large cities." —Testimonies, vol. 9, 167
"As Lucifer sees that we are making efforts to work the cities as if we meant to give the last message, his wrath will be aroused, and he will employ every device in his power to hinder the work." —Letter 74, 1910