Some H616 stock firmwares have been found with pre-installed "test-key" malware; custom ROMs offer a clean, secure slate.
Here is an interesting look at the state of custom ROMs for this silicon. allwinner h616 custom rom
If you hang around forums like FreakTab or XDA Developers, the H616 scene is currently dominated by a figure known as and his project, "Matrix." Some H616 stock firmwares have been found with