For Mg, I use TM only to raise a little and maintain the level and not to raise it when it is way too low.For that I do water change.I have epsom salt but still hesitate to use coz of the sulphate content.
For the SC additives it really is good.BTW all my dry 'dead rocks' I bought are now all covered by coralline algae within two months only.(save money)
I have yet to see any difference in dosing iodine though.
Overall, I am pleased with these products.Although having a CR is ideal but IMO it is also problematic.