Separating the main "/system" folder out of WWW root for multiple web apps?

[eluser]fesweb[/eluser]
I do it this way:

Code:

* the public url
/myapp/

* the actual application
/code/ciapps/myapp/

* the system folder
/code/CI_1.6.3/mysystemfolder/

This allows me to:
1. easily upgrade and downgrade any application independently from the others, in case something doesn't work with newer version of CI.
2. run variants of the same application at two different public urls (ex: "/myapp2/" could point to the same app).