I'm not sure what you mean by practise, I don't know how you'd practise' uninstalling a program. But anyway, a knowledgeable guy posted instructions on how to revert to v10.7
Here's the link . . .
The only working solution I found was:
But like it says there: perform it at your own risk - follow exactly the steps there - you might have problems when your IT Library is located on a ext HD... neevertheless you can reinstall IT11 with no problems if it doesnt work for you.