Move Developer Folder
Some files in the /Developer path are referenced when you launch specific functions within  Xcode. If you need to recover space and absolutely has to move /Developer, you could try


Move the /Developer folder to the alternate path and symlink it so
that Xcode still finds it at /. Note: I haven't tried it with Xcode 4.x, so please share if this works.
alternative is to do a clean uninstall using 'sudo
/Library/uninstall-devtools' and custom reinstall Xcode by
specifying a different path.