Since starting writing the IPv6 & Linux - HowTo it was my intention to enable a persistent IPv6 configuration which catch most of the wished cases like host-only, router-only, dual-homed-host, router with second stub network, normal tunnels, 6to4 tunnels, and so on. Nowadays there exists a set of configuration and script files which do the job very well (never heard about real problems, but I don't know how many use the set. Because this configuration and scrips files are extended from time to time, they got their own HOWTO page: IPv6-HOWTO/scripts/current. Because I began my IPv6 experience using a Red Hat Linux 5.0 clone, my IPv6 development systems are mostly Red Hat Linux based now, it's kind a logic that the scripts are developed for this kind of distribution (so called historic issue). Also it was very easy to extend some configuration files, create new ones and create some simple hook for calling IPv6 setup during IPv4 setup.
Fortunately, in Red Hat Linux since 7.1 a snapshot of my IPv6 scripts is included, this was and is still further on assisted by Pekka Savola.
Mandrake since version 8.0 also includes an IPv6-enabled initscript package, but a minor bug still prevents usage ("ifconfig" misses "inet6" before "add").