Have you heard about the studies done by Eric Borneman? He has shown that IO is qualitatively one of the worst salts. In fact, on another thread, I read that somebody in the company(forget who at this moment, but he was a big cheese over there) said that IO is meant specifically for FO setups, not designed for reefs. If you like their company, Reef Crystals was qualitatively one of the best salts and is made by the same company for a few $$ more. Little need to buffer, better mixture, less cyanno...much better salt from what the test showed. Just a little FYI, thought it might help in the decision on salt choice.
SITC will soon(if not already) by carrying Reef Crystals based on the determination in Eric Borneman's study. Some of her customers are doing some tests in comparison to the IO they used to use to see if there is actually a dramatic difference, but Borneman's study made him conclude that he would not be using IO anymore. This is coming from a person who claimed that he buys whatever salt is on sale.