siberian

I'm working with incernerate spec and just want to know what would be preferred for talent points in destruction between conflagurate and soul leach I can put 1 point in either. I don't conflag on bosses since I think it's dps decrease using up the global cooldown. With enough crit it probably could be a dps increase.
does anyone know the math of what would be more dps?
sitting at 28% crit unbuffed atm with about 1111 spell dmg.