I would definatley support this concept as the only guild interactions right now are Guild Sparring and Towering.It would also be great if they would add a Leaderboard of the Guilds who won the most wars as they got for PKs, Baddy kills and Spars.This certain concept would take graal to a whole new level and recruiting strong peeps in your guild would actually get meaningfull.
It would get even better if you could add Allies in the war with you.It would be a great reason for peeps like me to buy the Ally Pack.