The are not the same. There is a little big difference. so far as - a) up to the present moment b) up to a certain point, extent, degree, etc as far as = so long as or the point of well knowing one from what we start to discuss something

so far as = Information which has been established from the beginning to now as far as = Information which is given - but is offered as possibly being incomplete and is given with possibilities of being incorrect or being referenced to someone else (to blame haha). "Little big difference" I like it Tiulpan 4

I agree that these are not the same. I think it is worth saying though, that they probably would not be used. I think in a final draft, a writer would find a more clear way of saying this. That does not mean it is wrong. I just think the same things can be said in a way that you do not need to think so hard to follow the intricate meaning. Let me try: "From all the research that has been collected so far, here is what we know..." So far as is known = extensive research "From what we have gathered about this, here is what we know..." as far as is known = this is what we (not the whole world style of we) know so far What do you think?