Cutting Back Late Summer perennials

My "Autumn Joy" sedum loves the soil it's in; raised bed with a lot of organic material. I get maximum height out of each sedum (2 feet) each year. But as the long stems hold water and develop flowers, they get top heavy and flop over during their peak.

This year I have cut the plant back* (June 19) about 10 inches to see what the results will be. I understand the blooms will not be as big, but there will be more of them and the plant will not flop.

*cut sedum back in June and mums back around July 4.