Wow, that's what I'd call a labour of love. Fantastic mockup! So many wonderful details in it. Of course, the standard orchestral repertoire is arguably the craziest thing to do with samples, and the fact that you're posting the live orchestral version for comparison says a lot about your work and attitude. In a sense, it's like playing chess with Kasparov: you know the game is lost beforehand, but you still play your best. I absolutely love that (and I think it's by far the quickest and more inteligent way to learn any craft).
I think there're many things which clearly show the limitations of samples and are simply impossible to solve, but, if you're not too tired to try, two things hit me that I think you can easily improve (if you agree with what I hear, of course):
1) you could try layering a pp legato unisono line along the meassured tremoli that leads to the climax at the end of the intro (marked "sortono le ore del giorno") to make it sound more fluid and lyrical. That way you'll be able to still hear the tremolo clearly, but less pronounced (samples are always too obvious; in this kind of passages, if you listen to a live orchestra, most of the times you can sense kind of a real legato part even if there's actually none). I'm sure this is doable with the tools you're using.
2) the dynamics at the cello part (in the "sortono le ore della notte" section) are too bumpy to be credible, because the long notes inflate too much in relation to the weaker piqué bowing that preceedes them. I'm sure that's a tricky passage to mock up, but I think that's also doable if you temper the CC curves in the long notes (or avoid prerecorded swells if you're using them, or draw a compensating CC curve if the legato patch you're using inflates the note by itself), and again layer a pp spiccato patch on top of the second note of the slurred pattern (the legato patches tend to have too slow an attack to work in those quick passages, otherwise it sounds legato, but not present enough). This might be difficult or even impossible to fix, but I think it's the weakest part of your mockup, so it might be worth trying, given the amount of time you've spent with this, and the level of detail you're working with.
Again, fantastic mockup. I enjoyed it thoroughly.