Advantages of split flaps
With traditional “big flap” designs, the break from large surfaces is very deep in the section, which can contribute negatively in some instances. But having a split surface, it gives the aircraft the same benefits of a traditional “big flap” design, without the negative of a abrupt deep brake in the section. This gives improved L/D and lower speeds in the critical phase of flight “flying low level and in weak and tight thermals”. It also allows the use of a thinner airfoil for better legs, and delays the use of ballast.