Thanks Scott.
In my previous office, the file was around 110Mb but was a mishmash of revit & cad (lots of linked details), and was sooo slow to load (sometimes up to 15mins loading all the linked files) or when saving to central that it drove us crazy. The file we're working on now is about 80Mb with up to 4 people on it, and is running smoothly so far. We're about 80% done, so I'm optimistic that it's not going to degrade too much.
TB