If it's not causing a problem IO is still the cheaper choice. Some are having problems with Ca/Mg levels which can be attributed to their salt mix.
If your levels are OK and stuff is thriving I wouldn't change. JMO.
Adam
I think we need to be careful about saying something or other is the 'best'. AFAICT, we only have Oceanics claims about what is in their salt, no independent testing to confirm those results. Hopefully, the inland reef salt study will shed some light on the different mixes.