Newbie question. Where does Freeradius fit in?

I have done some reading re: radius in general and Freeradius in particular. When should one use radius? I have read that radius is useful when one needs a centralized user/password database. I guess that would be good when one has lots of remote access servers. I have read that radius is good when one needs accounting. We just need a dial in solution for 6 or so users. No accounting is necessary. What are the disadvantages of using a simple ppp solution that authenticates against the /etc/passwd file on a Linux box? We were thinking of using a pci card with 8 modems. Is Freeradius overkill for us or is it a more secure solution? Any advice/links to documentation would be useful. The Freeradius FAQ's don't address this issue.