My observation is Guild War is a favorite KH activity. But the length is brutal, interfering with family life, sleep, and work/school responsibilities, if played with appropriate intensity Some may like the extended schedule, but It seems to me that it's hard to sustain interest and participation over an entire week. It asks a lot from players. Guild leaders especially carry a big burden.
Would you consider more frequent, shorter wars? Maybe keep it down to long weekends. Maybe even quick flash wars that aren't on predictable schedules? You could reduce reward track but still keep it meaningful. Keep pass prices low so people would buy it more often.
2 * $2.99 > 1 *$3.99