IME IO needs lotsa calcium, alk & trace supplementation. prob reef crystals is better.
im sticking with TMP. it dissolves the best for me. Besides, i prefer german things (including cars, weapons, electronics) over french! Japanese ok (i hate Lexus), made in the USA is next best. Also TMP has lower silicates, even if copper is kind of in the high side.
Every salt had a bad batch, including IO & RC! frequent water changes on large tanks, using IO can save hundreds per year. Thats if cost is a concern...