Droprate question

I have been talking to a guildmate of mine about the Miniature Peacekeeper Enforcer and it's drop rate.

We are wondering how this exactly works.
Does every single enemy have an x.xx% amount of chance of dropping it?
Meaning that you could kill 1 foe over and over to have the same chance as killing all foes in the area that can drop it?
Does Normal/Hard Mode effect the drop aswell?

The basic question is, what would be the most effecient way of trying to get this specific minipet.

Don't include buying it please I know that's the most effecient way

Well many people say that drops are better (or at least more frequent) the longer you are in a zone. But in essence the droprate should be the same from any enemy that can drop that mini. Green weapon drop rates are affected by NM/HM, so I'm going to hazard a guess and say the green minis are as well.

I have to add something that you probably already know: the droprate of enforcers is extremely low.