I keep bumping into church leaders of different persuasions whose goal it is to see their church plants grow to 500+.
If you want a case study of how it's done, try the Southern Baptists. I've just finished a 1994 article by Roger Finke that shows between 1920 and 1990 the average size of a Southern Baptist church soared from 115 to 396. Impressive.
The other trend he noticed was the dramatic increase in seminary trained professional clergy. Before 1950 the Southern Baptist seminaries produced 10,000 graduates. From 1950-90 the number grew to 60,000.
The Southern Baptists heritage was all about small churches and lay leadership. Today it's professional staff and large churches.
Bigger churches. Trained clergy. Sounds like a recipe for success.