We are a data management startup and we are looking at building a web-based app that allows the setup and management of ftp users and ftp over s3 for businesses

We are a data management startup and we are looking at building a web-based app that allows the setup and management of ftp users and ftp over s3 for businesses. The rational: 1) web-based management of s3 is lacking and thus hard to use (e.g., you can't limit Frank to use only 5GB and Sarah to have 9GB) 2) s3 provides a "never ending" supply of centralized online storage 3) but users are not familiar with s3, but know ftp and have ftp clients Thoughts?