the only reason a result would look certain is because it only happens once. the so called technicalities in your illustration are exactly why its not always going to fall one way. thats simplistic cause -> affect, linear thinking.
i certainly don't believe in free will. free will seems a misnomer in the first place. it makes it seem like anyone can willingly cause spontaneous changes, that anything could happen from moment to moment. if i wanted to be in california smoking with hippies one moment and then suddenly the next be in japan eating sushi, that would be free will: bending reality to whatever you want.
i believe in free choice
. whats determined is the decisions that will come to us, based on how we've been born and raised and on our current environment, and those things will give us stronger preferences to make decisions in certains ways, but you ultimately get to choose what you decide.
strong determinism makes me think that with enough data (and it would be a colossal amount of data) one could predict the path of the future. the way i see it, if someone had all that same data, they could only predict the probabilities of the future, and the further you tried to predict, the most innacurate your probabilities would be.
It seems like preference exists, and can vary a result, but only if you don't look deep into the atomic level, where, if we understood fully, we would see that everything happens by logical process - even our preferences and choices.
The atmoic level is about the only place someone couldn't say that things are determined.