Just installed 2x8GB (totaal 16GB) 1600Mhz on a Mac Mini mid-2011 i5, with succes.
Used these modules: https://www.corsair.com/us/en/Categories/Products/Memory/Laptop-and-Notebook-Memory/Vengeance%C2%AE-%E2%80%94-16GB-High-Performance-Laptop-Memory-Upgrade-Kit/p/CMSX16GX3M2A1600C10#tab-tech-specs
Also running a 1600Mhz. Had RUN MEMTEST86 for some time, without errors and about 10% more throughput.