Please have guild stores sell banners, that look just like the tabards, that are only available to members and display the heraldry. Multiple sizes, all proceeds go to the guild. I'd love to see guild halls decked out in their colors.
And then just like when you leave a guild your Tabbard becomes white so to would the banners LOL. I'd do it just to have some plain white banners for curtains. Everything is either Red or Blue.