" However according to several posters on Slashdot, that setting isn't saved once you quit and relaunch Firefox."
These people are wrong; I just tested this in response to your post.
See #60; on my system the *setting* appears to stick to false, but the *behavior* reverts to going to the spoofed site. If may be that your configuration doesn't have that problem; if so that's good, but you may want to double check.