If you are stopping calcium, I wouldn't do the MCHC because its a calcium supplement - Microcrystalline Calcium Hydroxyapatite Complex. But if you just wanted to try a different form of calcium, it might be worth it. I tried both... I eventually got use to the Paramin but I guess my body didn't need it after all (considering the knee issues).
Right now I am doing exactly what you are doing with just the magnesium... leaving the calcium out.