I'm wondering, if something changed over years.
Which mirror I supposed to use for scripts which meant to be used to
build trinity on end-user machines from source (gentoo ebuilds)?
Now I use http://scm.trinitydesktop.org/scm/git/<package name>. Is it
correct, or there is something better?

I don't think it will make a high load any day, unless TDE will become
anyway popular, but you never know and it's better to ask...