Hmm. It says that gimp-forum.net doesn’t reroute HTTP to HTTPS, Yet, it does, as far as I can tell?
Also, no point about being too secure. At work, I can’t reach GitHub because my customer’s proxy replaces the SSL certificate, and Github strict policy forbids Firefox to make an exception. So, I can’t access Gihub. Of course, I can import a certificate for the proxy(*), but then it means completely trusting that proxy for all the sites which IMHO is less safe than trusting the established authorities.
(*) Not really needed, since FF has a config setting that says “look for corporate certificates in the Windows registry” but the result is the same.