rockstar's right, you can't go wrong with either as long as you do it right. i know that you're "not supposed to" but i have actually mixed fox farm ocean forest, light warrior and canna coco together at about a 3/1/1 ratio(soil/light warrior/coco) and had outstanding results. it's been some of the best "soil" i've ever used, super-light and airy yet retains water very well. i can really cut down the amount of perlite is use because the coco is good at holding water and nutes and making them available for the plants. i think a big key is using all organic nutes because the coco helps to buffer the ph thus eliminating the myriad of ph and nutrient lockout problems that many growers face. fox farm's soils are all organic but of all their liquid ferts, only big bloom is all organic. i ran supertea and budswel from the guano company, r/o filtered water, and purple maxx and gravity near the end, and the plants absolutely loved it! pulled almost 11 oz dry off 3 plants of s.a.g.e. and had the healthiest looking plants i'd ever grown.
cross my heart, hope to die...