I do ebb and flow, and I use 5'' baskets with only hydro-corn (porous clay pellets). I use lake water, but before discovering that worked great I used RO. I only add calmag (and it is whatever bottle I have on hand) when I need to when my source water is a bit low in it. And I only add a slight amount, but I do because I grow under high intensity white LEDs, otherwise I probably would not. I have been adding 0-50-30 PK from week 3-5 on-wards depending on the strain, but I dial back the MC to only 4-4.5 grams/G when I do. And the PK I add is from Home Grown Hydroponics (dutch nutrient), I only add 1/2 the recommended dose.
Bottom line is I'm sure the stuff works fine on it's own but every situation is different and the PK can add a bit of weight, but I haven't tried it on its own. Other people do though.