If you're growing coral, I think it's safe to say that you can start with any salt mix and have great results. What's really important is consistent attention to water quality, which means keeping your nitrates down, and your salinity, pH, calcium, alkalinity and magnesium properly balanced. Some salt mixes might mix up with a lower Ca or Alk, in which case you'd need to supplement right from the start, while others may be high and you'd need to wait a bit for the levels to drop before supplementing. A lot of us use Oceanic, which seems to start off with high Ca and low Alk, but I like it because it goes into solution a lot easier than Instant Ocean.