The solution to all the cheats/exploits is four-fold:
1. Evony can work to tighten up the code in general: examples: validate information and flag accounts. You shouldn't be able to play with 0 disk cache being caught for example. Information should be validated against expected data sets for a given amount of time to make sure it is reasonably accurate - in some cases people have used more sophisiticated exploits to abuse this. IP addresses should be pinged - any matches should be automatically flagged for suspension/investigation (that's a minor piece of software that would catch at least some of the multi-account people.)

2. In-Game mods that can read reports, perhaps look into logs, and research abuse reports. Essentially, they could see anything the players see plus maybe some historic reports that individual players (but not alliances) could see. They could read what an individual did for a week to see if it all adds up. Give them the ability to place players on holiday for 3 days if they find infractions and have them send their report to Evony for final action/judgement. They could be paid in game cents (requiring no money) and just be prohibited from doing anything on the servers they monitor. A group of 2-5 per server would suffice. You would have people lining up to volunteer to help.

3. Limit army sizes - take out part of the incentive to cheat. Have an equivalency unit (say 5 warriors=1 archer) and limit someone to 150K units per city they own (and they can move these to wherever they want.)

4. The players and alliances should promote something of a code of conduct. If the big alliances support a fair-play idea and refuse to accept players with multiple accounts (if known) or otherwise approve of cheating, the cheaters will be in a minority and be pretty unpopular people overall - ultimately leaving the game.

If all 4 of these were done, Evony's playing field would be level and your player retention rate would improve. You would also see more people invest real money into the game more frequently (such as having a subscription level that has some mechanics benefits (like doing a set of farming runs for you (with a maximum) or dream truce for free every night, etc.) that reduce time requirements.)

Let's hope they act on these!

Felwred