Tattu 1300mah 5S R-Line with the GemFan 3D Master Prop along with my 2010-2400kv motors and KISS 24amp ESC's is my new favorite power system. Going from a 1550-4s to a 1300-5s is within a few grams of each other, meaning moar power without changing the way the quad feels to much- overall feeling more locked in.
I'm going into R&D and practice mode right now- trying out new hardware configurations