Neopan 400 is nothing like Acros tonality wise. But Plus-X is also different from Acros, so the question is difficult to answer if not impossible.
I think Tmax 400 would be closer to Acros because it's linear. Neopan 400 has a pretty abrupt shoulder (which compares well with Ian Grant's observation of high contrast), which you have to be wary of in processing. With that said, Neopan 400 is capable of stunning results. Any film is, actually, and a lot depends on how you use and process it.
Master printer Andrew Moxom of this web site uses both Acros and Neopan 400 side by side. He processes Acros in Diafine and Neo 400 in Pyrocat. The prints from his negatives of either kind look very cohesive, so an all Fuji lineup would be worth a shot.
- Thomas