Death penalty citadel upgrade = total waste of gold. That's terrible.
The final spot on death penalty should allow dead players to spawn anywhere they want. While they're dead they can ghost around and choose their spot.
OR... from the very first rank, players can choose their spawn point but it has to be within 15 meters of the health crystal. Further ranks would increase the spawn range.
OR... in addition to reducing respawn time, these upgrades would grant extra gold when your team kills an enemy DG.