The engine already stands. the missing 40% are not optimization but content. Look at the FFXIII demo which also was based on an early build. Apart from the different menu design it was virtually the same as the final game.
And this is always the case. With every demo or "beta" nowadays. People let the devs get away with everything saying "All criticism is invalid because it's not the final build and everything will be better in the final game!". Which is pretty much never the case.
I don't really believe in the FF polish anymore after I've seen LR. It's a different time and the machines are weak. Devs these days just love to sacrifice performance for spectacle. And you know how much SE loves spectacle.
Come on Vis I expected more from you.... How can u possibly say the missing 40% is content. We just don't know that. More so how can u say its not optimization when everyone knows that optimization is the last thing that goes into a games development.
I believe that SE know they have a lot to prove with this game, and I also believe that they will get it right.