The different of dropbox and box.net

I think this is fine if you are only testing something for a few friends. However, there is an issue with using too much bandwidth if you try to host something through your public folder that becomes too popular. As per https://www.dropbox.com/help/45:

There are currently no hard limits on public bandwidth usage. We do, however, have an automated system for detecting and flagging unusual amounts of bandwidth usage. We will send an email notification whenever an account is flagged. Once flagged, public links will be temporarily disabled and users who use the links will see an error page instead of your file.

I am assuming they are talking about the Dropbox application on your computer experiencing performance issues with a large number of files, and not that your teams account would experience any degraded performance server side. I currently have over 100,000 files and have not experienced a drop in performance. I have heard of people with much more, I believe at least 400,000.