I think if your just setting a tank up you should be akay using API, although if $$ is no object, Sailfert is the way to go. Just a little to pricey for me and they are more complicating to use. I will switch one day to Sailfert but right now I like my money and my API gives a pretty accurate reading.
I guess I feel with the API I can tell what adjustments need to be made as far as nitrates, pH, Ca, etc.