I’m a Firefox user but I’m not sure that I can agree that it’s lighter than Google Chrome. I think Chrome is generally faster at everything. Chrome is also more stable. For some reason my Firefox randomly freezes once or twice a month and gets stuck in a crashing loop where only a reboot will fix it. But on principle I use Firefox whenever possible. I appreciate the effort that went into it. Still have to use Chrome…
Personally, I have found FF really stable lately on both Windows and Linux and use it whenever possible as you do. And like you, I also need to fire up Chrome for the odd thing now and then.