New General Ledger

Hi...We are about to migrate from our R/3 4.6C to ECC6 in the coming months. However, we do not know whether to migrate also to the New GL. So far, we are happy with our old classic GL. Are we going to continue to use our old classic GL or also better migrate to new GL....We do not know what are the benefits of shifting to new GL & how long the project will it take to migrate from old to new GL.

Appreciate your advice...thanks