i dont get what leading the flop acheives here?

If your opponent clearly hit the flop or its a gross flop that you can bet/3bet (perhaps bet/3bet AI) and get away with doing it without just nut hands (sets/straights/combo draws) then id like your line - but this isnt - you clearly arent going to have many nut hands vs the top end of his one pair/FD overs range that you play like this ( i think playing a boat this way is pretty cool)
Therefore i dont see how your line is good - if there is a chance your hand is good on turn then id call and use the spades to bluff at giving you ~30% the remaining cards to play with that you can play when you may have nut hands here.