I've seen about 80% of your list, so I feel I can say something about it. Overall, it looks pretty good. That said, let's commence the caviling.
First of all, I guess we disagree about the importance of von Stroheim. (You even handed Victor Sjostrom the credit for directing Greed!) He has his faults--at the moment, what stands out is his occasionally grating use of overt symbolism--and we don't have the films he intended us to see (and, of course, the fact that he didn't have much input into the final cuts of his films complicates our sense of him as a director). Still, he stands out to me as a major figure, and I'd keep Greed on this list and add both Foolish Wives and Queen Kelly. (I'm not sure whether you've seen the recent restoration of Greed--you know, the one with the stills--but I wholeheartedly recommend it.)
Second, Lang's silents. I suppose I ought to preface this by saying that Lang is way up there in my personal pantheon (M might be my favorite film and I share that Cahiers-inspired mania for his American period), but I don't share the widespread enthusiasm for Metropolis. Maybe I'd change my mind if I saw a nice print in a theatrical setting, but I'm currently inclined to doubt it. There's no question that it succeeds as spectacle and that it's a masterpiece of architectural design, but I'm afraid it just seems woefully shallow to me. Of course, it might just be that it seems intellectually jejune when compared to M, and I guess making such a comparison would be unfair, as I consider that film a model of intellectual depth and clarity in the cinema. Or it could just be that I'm skeptical due to the cult status of Metropolis; you know, maybe it's just my cinematic snobbishness rearing its ugly head. So, what should we put here instead? We've gotta have something by Lang: there's no question that he's a major silent film director. Unfortunately, I'm not really qualified to say. (I must say it's more than a bit embarrassing to admit.) I've seen Spies, which I enjoyed quite a bit, but, although it's a nice thriller, it just doesn't seem to have the depth or historical importance to warrant a spot here. And, honestly, that's all I've seen at the moment. I plan to watch Siegfried and Kriemhilde's Revenge here pretty soon, and I hope to get my hands on that new DVD edition of Dr. Mabuse, Der Spieler, so maybe I'll be able to add something before too long.
A few films that I think belong on a list like this:
1. Vertov's Kino-Eye. It's been a while since I saw this, but it was an extremely pleasurable experience. It's not quite the visual feast that Man with the Movie Camera is, but what is?
2. Pabst's Joyless Street. Honestly, I think this far outstrips Pandora's Box. This film reminds me of Mizoguchi's Sisters of the Gion in its depiction of how two different women react to the terrible options provided to them by the society in which they live, and it even seems to display some of that palpable anger that I associate with those early Mizoguchi dramas. (Of course, maybe my previous acquaintance with Mizoguchi led me to read something into the film that wasn't there, as just about everyone else I saw the film with--I saw it in a classroom environment--thought it was nothing more than a piece of rank didacticism intended to convey the following moral to young German girls: be good bourgeois ladies or you'll end up whores.)
3. Murnau's Tabu. It deserves to be on here for its ending alone (which is of more value than the whole of Nosferatu as far as I'm concerned). The rest of it is pretty good too.
4. The cream separator scene from Eisenstein's The General Line/Old and New.