it would have no effect, mine is changed constantly, at 100% each time, with all forms of salt. the lfs selects which they buy and I do 100% water changes on 10 yr old system only because its small
at any given month im on kent, esv, oceanic, coralife, IO, RC etc. don't even know what the current is, kent I do think per last asking. im not having to dose much, so I don't mind whatever the levels are. one mix's higher alk vs another's lower isn't impactful, only to the alk you might add. how they actually mix up wont kill any corals.
all salt mixes mix up differently, and each coral tolerates this variance. its your dosings that must alter after each change. whether the tank is swapped whole or in part doesn't matter if temp and salinity are matched.