I did read through the site, and though I did not download the tool and try it out yet, the site seems to be catering to an individual who is used to SSHing in to / FTPing up to a site and hitting refresh (I did this when I was first learning about the web way back when as well, and I can appreciate the productivity gain here).
The hosting of your CSS files on their servers is also not suited for a development environment that has more than 1 environment, as I would not want to be editing files that are on a live server on a regular basis without first making those changes locally (and possibly checking them into an SCM of some sort first) because my css would quickly become out of sync across environments.
May I ask, the projects that you work on, do you have more than 1 environment that you use and do you collaborate with any other developers on these projects?