How I broke mine in last month (some would say it's still breaking in):
First 100 miles, easy, no full throttle, use engine braking as much as possible, vary speeds constantly.
101-400 miles, still want to vary speed constantly, however, now you want to use all throttle positions including full open and dont pull clutch and coast, use the engine braking. Gradually raise the RPM you run up to, until by 400 RPM you are hitting Redline or just shy of it.
401-500 miles, ride it, ride it hard, ride it like you fking mean it. Don't abuse it, but do use all of it. Getting on a freeway? WOT in 2nd gear till redline, 3rd too if you're feeling fruity
Getting off a freeway? WOT in 2nd gear till redline.
Get your service at 500, then ride however you want to.
There is a plethora of anecdotal evidence and some hard evidence that babying an engine early in its life is the worst way of breaking it in. The goal is to get maximum cylinder pressure/vacumm applied to the rings, it slightly flexes them and cleans off the edges of the cylinder scoring and the rings themselves. This creates a good mating surface and will last a life time.
Additionally, bearings, you will want to be gentle very early on (0-100 miles) to ensure the assembly lube gets time to be washed away and any imperfections are smoothed out, this absolutely doesn't take 1000 miles. The reason my method slowly ramps up the intensity is to allow this early friction surface cleaning throughout the engine. The 101-400 period is for the benefit of the rings/bores. The 401-500 period is really to identify weak or out of tolerance parts. This is the period where I want it to break if it's going to so it will be caught at the first service.
Bottom line is: All vehicle companies have good reason to say "baby it the first xxxx miles".
First: It is in their interest for you to ride easy as you get used to the bike, safety reasons.
Second: It ensures if you do have a critical part failure, you wont be going super fast.
Third: It disuades tards from going out and buying a bike and tracking it the same day then trying to claim warranty work on an un-proven motor before the first service.
My method has worked great for my last 3 vehicles, including the rocket, which I have the dyno sheet posted on this board done with only 681 miles on the odo. putting down 127/145 stock bike with a downloaded tune not a custom one.
Last performance engine I did was a Turbo 2.0L 4 cylinder making about 410 hp that I drove daily, raced often, and lasted 60,000 miles before it finally broke a ring land when I was drag racing in Arizona on a 105f day, whoops:-/