Number of repositories should not be decided based on number of users.
It depends on the number of client machines and their locations.
If you haven't already done so, have a look at the ePO 4.5 Best Practices guide, available here: PD23051 . There's a section in there for repository calculations that I think should help.
Thanks! We have been having some botlenecking goingon and wehere looking for the documentation to bring to budget. We have a spreadout infrastructure with only one Repo for the main campus of about 13k nodes. I have been trying to recomend adding one per 3-4k nodes to help with this.
No problem. Bear in mind that you need to have quite a few machines at a particular site before it's worth putting a distributed repository there (in terms of bandwidth).
You also may want to think about the MA 4.6 lazy caching option, which will be available very shortly. Depending on your environment this may greatly reduce your bandwidth usage.