I have used supersoil with very little problems. If you go with ss then I would suguest that you add some nitrogen and phosphorus. I have noticed early nitrigen def using this soil. I have used a 4-1-1 fish fert and 15-30-15 (for flower) with good results using this soil. Check it out in my sig. Although the soil is supose to be 5.5-6.5 ph wich is not great for MJ. I am currently expreimenting with organics with the use of this soil and I am having no problems yet (nock on wood!!). Good luck!!
KM