I hate to be the bearer of bad news, but I called the theater for you and spoke with the manager. The Regal cinemas IMAX screen in New Rochelle is indeed one of the huge six story tall screens, as they used to show 15/70 film. Sadly he told me that they are showing The Dark Knight Rises digitally on that giant screen.
With the current digital projection system that IMAX has, it would likely look worse on their giant screen than if you saw it on a smaller "LieMAX" screen.
I'm guessing they've made the temporary switch to digital in preparation for one of IMAX's next gen digital systems. In the meantime, New Rochelle should be scratched off anyone's IMAX list. Or at least call the theater and ask the manager if they're showing the current IMAX release in film. A 15/70 film screening there would be the real deal.
