Please add to the ccache instructions, concerning the variables in /etc/portage/make.conf:
There is no drawback for adding this for portage compilation, and it will increase the number of hits in the long run (when upgrading packages). Also, in my experience adding the variables
are a good idea (and even the latter, though apparently aggressive, never caused any troubles for me).
Nevertheless, one could mention that changing such options invalidates the previous cache content (the first at least partially) so that immediately after the change you will get less hits.
Problems with sync-uri and sync-type = webrsync
Deprecated FEATURE in Validated Gentoo repository snapshots section
Following the instructions I discovered that the "webrsync-gpg" feature is deprecated and results in the following warning.
emerge-webrsync: warning: FEATURES=webrsync-gpg is deprecated, see the make.conf(5) man page.
The page should be updated to reflect the "sync-webrsync-verify-signature" setting.