Defensive Gates 10x HP & 50% Quicker repair.
A couple of simple number upgrades to defensive gates 1-4
I found that a group of 15-20 naked cannibals or fogmen could blow over level 4 gates in 5-10 seconds, even with a team of repairmen behind it.
10x might seem like a lot, but your standard "The Fog" & "Mighty Canhead" raids will take about 1 minute to break down a level 4 gate if no one is repairing it. Stronger groups like Samurai or Holy Paladins will do it in less, but that makes sense.
I upped the repair speed by 50% so that repairmen can actually make a noticeable difference when repairing during an attack, but I did not want it high enough so that 1-2 people alone could negate the damage of a low level attack, a decent team of emergency repairmen will be needed to holdout longer than a minute.
Mainly made this because the gates fell so fast, that when I was running around away from main base, by the time I saw the tab flashing, it was already too late to prepare.
(Thanks to Shidan for the crash course)