To be fair, we have to realize that there <b>will</b> be some chemical interaction/reaction to a change such as using a different brand after using one kind for so long.
I used IO for a brief period of time, but to be honest I switched to Kent because it cost a couple dollars more. I felt it might be better. Later I switched back because I was broke :lol: but found IO didn't disolve well. Some of my livestock was burned by the white dots of salt that landed on them, and I swore never to use IO again. I used Kent for years, no matter what anyone else used. I know that many on RC followed the report by Ron about Bio-Assay salt after he declared it was good enough for baby urchins so it was good enough for our tanks... but I ignored it. The massive swell to use Bio_Assay made that company rich briefly, until the mass outcry that their tanks were crashing (chemical interaction/reaction is my guess). People with new tanks using that salt had no issue, but established tanks plummeted in health due to the switch.
When Oceanic came out, I got my 5lb sample and mixed up a bucket of water and tested the water. The numbers were good. I believe alk was 8dKH, which is good enough (NSW is 8 to 11 dKH), plus Mg and Ca were nice and high. So I made the switch. I change water about every six to eight weeks and haven't attributed anything negative to the salt. Some corals just go belly up for no reason. I never get algae outbreaks, probably due to my use of refugiums on my tanks.
So that is where things stand. I just opened up a new bucket of salt this weekend for a 50g water change, and have 5 more buckets of Oceanic. I'm sure I'll continue using it unless something solid comes out that causes me concern.