i installed a brand new engine, rode it 35 miles non-stop at WOT to a motorcycle show, then rode home another 35 miles a few hours later. a few thousand miles have gone by, and the motor's still going strong.
opti-2 oil and "blueprinting" the motor before install virtually eliminates the break in period.
("blueprinting" is a relative term, since no one knows what these motors are supposed to be spec'd at...)