Brian, Thanks for the feedback - yes I think two T-1s or maybe even one is overkill. But you do have to consider the WAN infrastructure before determining sites. The number of users is a factor if you consider each user is probably on a workstation. In the scenario we never had the information of why a separate site was being decided.
I'm not sure the person in question really needs a site and that's why I'm asking these questions -- you could technically have a fractional T-1 link and a handful of users and still stay with a single site rather than having a remote site. There are two areas of consideration -- authentication traffic but also replication traffic so both have to be included. I've personally found that a lot of people will decide to create additional sites when they often don't need to be created. Regards, Chuck