WLSJ,
This might be useful in a scenario where you have two tunnels on the same head-end router terminating on two different tail-end routers that are connected to some downstream networks.
If you want these networks to use one tunnel rather than the other, you could simply use the relative keyword and add to the default metric, which would normally be the shortest IGP metric to the tail-end.
Bottom line, it just adds more flexibility.
Regards,
Regards,
Harold Ritter, CCIE #4168 (EI, SP)