I have an FSA SL-K Light Hollow that came with 53/39. I switched to this 50T(130mm) and kept the original 39 small ring...NO PROBLEMS!
Shifting is quick and smooth even under load (I use a Shimano 7900 front) and the 50/39 combination has proven great on speedy flat to rolling country terrain, be it solo or club rides. I have found riding in groups at higher pace sometimes forces more spinning, but at 5'-7" I can draft to keep up - works for me!