If you are planning on using an IGP (the GPU that is integrated into a CPU) for gaming, the faster RAM can give you significantly better gaming performance.
For the vast majority of all other applications, the faster RAM will not give you any significant speed boost.
If you have and AMD APU and plan on gaming with it, definatly get the faster RAM.
Otherwise, the 1600MHz set will give you identical performance for a much lower price in all but a few instances (mostly in synthetic benchmarks).