Potential problem Rated 5 out of 5 stars
I think I have found one potential problem, at least it was for me. The patterns are case sensitive and I don't think that they should be because URLs are not case sensitive. I was going to the wrong proxy as a result of my URL having some upper case letters within. It apparently didn't match the lower case URL name on the site and was thereby going through the wrong proxy.This review is for a previous version of the add-on (2.6.2).
Version 2.6.3 will have a checkbox to enable/disable case-sensitivity per pattern. By the way, URLs are only case-insensitive when the webserver runs on a Windows-based machine. When the webserver runs on unix, linux, or other case-sensitive operating systems, URLs very often are case-sensitive (although not always). You can see an example by visiting http://foxyproxy.mozdev.org/proxylists.html (valid) and http://foxyproxy.mozdev.org/proxylists.HTML (invalid).