Some of the anti-MO posters in this thread (assuming they’re not all the same person, i.e., Joseph) are making a mistake by definiting Modern Orthodoxy in terms of Torah uMaddah. I’d guess that if you asked a bunch of self-described Modern Orthodox Jews (from the US as well as various other countries) what being MO means to them, most of them wouldn’t say anything about YU or TuM or “the Rav.” After all, it’s not as if all MO go to YU and define their religious identity in terms of the Rav’s philosophy.
I believe that most MO Jews would say the following: being MO means being Orthodox but not wearing a uniform associated with those farther right (black and white, velvet kippas, etc.), not having a bias in favor of more machmir interpretations of everything, and holding by rabbis who dress and think like them.
If this is indeed what MO means in practice, then at least according to these variables, DaMoshe may be right that MO is most consistent with pre-haskalah Yiddishkeit. Jews didn’t have a conformist uniform before the haskalah (aside from das yehudis); that probably started with the second or third generation of chassidim and spread to other groups after that. The present drive toward increasing stringency among the right-wing of Orthodoxy today didn’t exist yet, because that came about as a reaction to haskalah and reform.
However, there may be other ways in which charedi Judaism today is more consistent with what people believed and practiced pre-haskalah (such as people’s attitudes toward mysticism and Torah-science conflicts). It just depends on what variables you’re looking at.