Similar to what Benjamin mentioned, Schaumburg installed the AIM modules on our units, but kept running into issues. Ultimately, the same decision was made. We removed the AIM modules, utilized ProKeys, and the drivers enter the meter reading themselves.
We use Fuelmaster and started using the AIM modules on our vehicles as it is supposed to make fuel and milage reporting "idiot" proof. We had a few vehicles that would throw all sorts of check engine lights and have performance issues. Everything traced back to issues with the AIM module causing the issues. Since then we have just gone to ProKeys and the drivers have to enter mileage. Other than a few that cant remember the mileage from the vehicle to the keypad, a couple feet, we havent had many issues that way other than occasionally having to reprogram the ProKey.