I would definitely break it into sections. You can do this cheaply by upgrading to Quicktime pro for $29. You can cut the film into sections there and then rexport the qt or avi file... Depending on you system's capabilities and how much juice you're using for VSTi's, effects, etc., a large video file will only slow you down. I generally break my files down into sections of 20-30min and then reassemble after I'm all done.
Since they're shooting on 24p and if you need to sync to exact frames, you'll need to get a file that runs at 29.97 and then do a pulldown later.
Otherwise if your files are 23.97 fps, your timecode won't be in exact sync. I just did a project like this and it worked fine, it was just a bit of a pain not to have the tc line up exactly. If your doing more sound design stuff, like effects, foley, etc. It's going to be a huge pain to sync up.
I hope the 23.97fps framerate support is included in sonar by the time I start my next project (also shot on 24p)....
Ron or anyone at cake care to comment on whether this is a planned feature for v5?
-r