I moved from ATL last April, and I never saw much of a difference between using the Main security checkpoint and the elite line. The lines can be long, but they are always moving. Generally TSA is good about having enough lanes open to support the number of pax in line. Even with a line out to the atrium, I think 20-30 minutes is the longest wait I have had. I maybe went thru security at ATL twice on a non-Monday morning though, so my experience is largely based on the Monday morning rush.