I really like this add-on, especially the new icon update, it looks much nicer.
I'm not sure if it has been fixed, but it seems to have a slight mem-leak, once i left it on for 48hrs, came back to my computer and it was CRAWLING, I checked the task manager and it appeared to be firefox, I closed the FireFTP tab, and everything was back to normal...
All in all: Great FTP, if you don't leave it open for more than a couple hours :p.
The Best! You could have the option to only activate it separately. Because sometimes I want to access the FTP through the browser and not through the extension. And it's hard to have to disable the extension, restart Firefox for this.