I strongly believe that most all 'Salt Mixes' today are very high quality in general and really depends on your tanks needs and/or your maintenance routine.
I have used regular I/O for over 25 years with no issues in all types of Reeftanks. Have also tried a few buckets of Reef Crystals and SeaChem Reef Salt. Just recently made the decision to go with SeaChem Reef for a year or so to see if there is any real positive effects long term with its use. I made my decision in part because that SeaChem Reef mixes at 1.026 and not 1.022+- as does I/O salts so 160 gallons or 200 gallons mean just that. My routine for many years with I/O was very simple and affordable getting it to or stepping it up to Reef specs and 1.026 S.G. For a 15 gallon SW batch I added 8 rounded cups of I/O salt, 1 Tablespoon of Tech-M and a heaping teaspoon of Calcium Hydroxide (Kalkwasser) so I figure for just pennies this mix was an adequate match for much more expensive Reef Salts.
Cheers, Todd