Salt selection in western Canada is terrible

[Cujo#31]

The only real difference (feel free to correct me here anyone) is in the guaranteed analysis of elements in any given salt mix. As Albert says, used one, used them all.
"Higher grade" salts claim they can be used as soon as 2 hours after mixing (although I have never pushed that envelope) while many salts recommend a 24 hour stand time.
As long as you stick to the bare bones basics of any reef tank husbandry practice which is to test and match perams you should not have any issues.
Other mixes are just more convenient in allowing us to not be so concerned about dosing to top up as much in certain elements after we do a WC.
I used IO for quite a while and really only found that the salinity tended to vary a bit from batch to batch and I learned thru trial and error to leave enough room in my mix barrel to fine tune the water before I completed a change.