I think your browser does a better guessing when charset is missing in the headers.
In all honesty I suspect it is just luck. Under Tools->Preferences->Content->Fonts & Colours->Advanced->Fallback Character Encoding I have "Default for Current Locale" set. The $LANG is en_GB.UTF-8 but viewing the not-logged-in Monastery Gates the content encoding under View->Character Encoding is "Western", ie. Latin-1. But under "View Page Info" it is "windows-1252". Make of that what you will.
Pale Moon looks interesting.
It is indeed. I've been using it for the past 11 months and it is, in general, really very good - like how Firefox used to be before they canned all the useful stuff and broke most of the add-ons. I've not knowingly used mozrepl so can't comment on that.