Argh. Beat me to it! But yes, this is correct although you will have to open to LAN every time you load the world.
I use this feature to investigate redstone wiring on custom maps!
Here is how I'd do it:
- Backup your world (just in case something bad happens)
- Note the seed number using F3 (or the seed text if you remember it).
- Create a new world with same game version and same world creation seed number (or name).
- Make sure that new world has CHEATS ENABLED.
- Copy all region data files from the old game world, to the new game world.
In Windows the region files should be in a folder a bit like this :
You should now have a working "copy" of your old world that now has cheats enabled without needing to open to LAN every time you load the game. Or needing to go get a secondary app like NBT helper or the like.