acros and tmy2 are the only films I use for night work...

not that I'm an expert or anything but I've done enough testing to use them
for my meagre purposes

I did a bit of exposure bracketing using acros and pretty low-light,
http://www.flickr.com/photos/stormiticus/4769811341/

I've done the same with tmy-2, came up with about 9 minutes for a full moonlight scene...

I guess I'm saying you'll need your own tests, but then you'll 'own' those films,
i.e. really know the film's capabilities from experience