I have used and saw many grows where MG is used. 9 out of 10 times new growers use it, and also add nutes early in growth leading to nutrient burn. Its soil loaded with nutes, so no nutes are needed until the plant shows you it needs nutes. On the other hand i have seen grows where MG was used by experienced growers had no problems occured.
Also i think there is something in MG, that can not be flushed out during the last weeks of growth before harvest. This will leave a taste in the finished product.
In my opinion, If you really can NOT find any other nutrients, and can NOT locate any organic soil, then use MG with Caution. But I would suggest spending a little more on a 2 or 3 part nutrient solution than the extra money you will spend on MG soil compared to Basic potting soil.
Walmart carries a soil called " Sta-Green" That I have used for years. Very little nutrients in the soil, so it wont burn seedlings or clones.
Hope this helps ,
Lilmafia513