Several suggestions about gangland dungeon -

It costs 15 sot per run and 250 fc for a key. That is basically the same as any 'big' frontier dungeons. But it is open only for 1 hour and drops only one evo shard at a time. Compare that to dungeons like ravens alter, samurai or powerslave dungeons etc. These drop 2 evo shards per run for the same sot cost. Making gangland drop 2 shards per run would be cool. Right now there is no reason to play in gangland dungeon once you get gangland Eddie.

Three star yellow evo shards only drop in the labyrinth and gangland dungeons. Making this change to gangland would help in farming for yellow shards. Right now labyrinth is the only reliable way to earn them. The drop rate there varies between 20 to 40 per key. That would mean using at least 15 keys to get enough materials to max ONE character.