Sounds like a good fit to me.
FM was designed for, and excels at, long document publishing, particularly handling multiple files as a unit. Think of each component file (chapters, drawings, whatever) as objects that are managed by a container or meta-object -- a FM book. By contrast, Word is a word processor and has never been good at even single long documents, let alone a herd of them.
Further, FM is a component of the Tech Comm Suite, which includes RoboHelp to generate help files, and RH includes an AIR/Flash packager. So you'd probably be able to design your workflow within the TCS to take advantage of hooks between the component programs.
And, if you wanted, you could still go to print or PDF from Frame.
Art