I don't know your setup that well but if you are using dividers or voltage references, think about what kind of resistors /Vref you will need in order to maintain the comparability of 16-bit adc from source to source.
With a good layout engineer and a good analog engineer, you may be able to get a 16-bit adc to work in the real world environment. But that requires a lot of work and luck. Most people end up doing is discarding the last few digits.