6 of one and half a dozen of the other @paul_led_126pro
Peat based composts have a natural tendency to go acidic, ie : for their ph to drop over time. If you amend your soil at the start using lime as an additive it helps to prevent this, while also providing Mg for the plants, meaning fewer problems during the grow and less need to start ph up and downing. But, there are strains and setups (such as LED's or water in certain areas) that seem to need more Ca, so it's always handy to have something like CalMag in stock so that when, or if, the Calcium def rust spotting occurs you can give them an instant fix if needed.
It all depends if you are going down the 'let the soil do the work' or 'get them on a feeding schedule' method of growing. As you seem to be veering towards the 'feed them' method, then the Plant Magic range (developed for UK water/growers) sounds like the way to go