whoops!
Hate to say it, but it is very true, but may not hold true for every brand or every bike. You could always wind up with that one bike that was the last on the assembly line on the last day of the week when everyone was concerned with one thing, getting home for the weekend. Dodge, Ford, and Chevy have had problems with this for years.
My 2002 gixxer 750 had a "race break in". It most definately has more power than any other 750 I've ridden of that year with the same mileage. However, I do recall that part of the reason that Yamaha's #1 cylinder issue in 1999 was discovered was thanks to a racer that "broke in" 3 engines and all 3 blew the #1 cylinder, thus leading to Yamaha testing and recalling a lot of engines because of a bearing that wasn't tightened at the factory.
Almost forgot, my 1999 Honda CBR RRX Euro had a somewhat hard break in up in Canada. The funny thing was with 10,000 miles on the odo it would still outrun most stock 954s and give a liter bike a hell of a run for it's money when it should have quickly faded away with the technology today.
Simple answer to the equasion is: if it voids part of your warranty don't do it. If you know someone at a dealer that wouldn't turn you in for abuse of that vehicle, then take your chances as you may.