If it is the reference to which I think you are referring, the main problem is the devil's in the details, which most people don't register. The instructions are on how to change the location of your media folder, not the whole iTunes folder. It does say that in the header but people confuse it with moving their iTunes folder. If you just relocate media then you need to keep the library files and artwork, etc, in the original iTunes folder. The library files have playlists, playcount, and basically tie all the media files together.
iTunes for Mac: Moving your iTunes Media folder - http://support.apple.com/kb/HT1449
If you want to move it all to a different drive then you need to copy the whole iTunes folder and everything it contains to the other drive, then restart iTunes with the option key held down.
Of course the other tip they omit is making sure you back up your drive completely before undertaking any major change such as moving files or updating software, just in case something unexpected happens.
Changing the media folder location in preferences tells iTunes where to put new files, not where to look for existing content.
If the library is self-contained, that is an iTunes folder containing a media folder then you can move the whole iTunes folder to a new location and hold down option when starting iTunes to open the library in the new location. iTunes will use the unchanged relative paths from the library to the media and "just work". If, however, the library is split as a result of moving the media folder the "recommended" way, then you should use the same process of consolidation (let iTunes copy everything, then manually delete the old copies) to move the media folder again. If the media folder stays put you can move the library files to a new location, and if that location happens to be the parent folder of the media folder, then you can rejoin a split library to make it easier to manage in the future.
As long as you have a backup of your old database it ought to be possible to repair that version of your library and then move it in a way that doesn't break it. Up to you whether it is worth the effort.
I put in a suggestion via the hosts that that article be made a bit clearer on the limitations, and to make a similar article on how to actually move the whole iTunes folder to another drive. You could do the same at
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