I was using IO, because of the info in my sig. From the same link, I decided to try SeaChem Marine salt (it was on sale also). The batch of IO I got had an alk of 12dKH, too high for me. The SeaChem is a steady 10dKH, I dose the "missing" trace elements anyways.
The only issue I've have with Salinity in the past, is the calcium precipitating out.