There were many topics about fully rebuilt engines. Now I plan to change only the piston rings, nothing else.

Should I break in the engine after the change or should I drive strong from the first kilometer. I have read this document http://www.mototuneusa.com/break_in_secrets.htm , where it is described how to make the break in and WHY. Some other people told me to break it in in 1000miles or so, but didn't tell me why. So, if you think I should break it in carrefully, tell me please WHY. If the break in should be hard, WHY?

Anybody did break-in after new rings installed? How? What are the results?