Just thought I'd emphasize on the fact that, indeed, Demigryphs come with their own proprietary base-size, which is not a chariot base. It has been pointed out already that the bases are 75x50, so if you went for the DGK variant, do jeep that in mind!
I think they would surely make a great eye-catcher especially in infantry units as fillers... You could "dioramise" them a bit, too, which sure gives you many options.