I hope that this whole break-in debate doesn't take the serious turn that I saw when I used to participate on the VFR mailing list. There it turned into some kind of holy way with lots of hot headed debate with little in the way of facts on either side of the issue.
On one side, you had the racers and power freaks that followed the 'break it in like you'll use it' rule and worried more about initial heat cycles than mileage and RPM, and on the other side you had the literalists that never even once revved past the limit in the manual. I took a few things from watching this debate for months.
1. Modern engines are so well made and precisely machined that it just doesn't make much difference. If you don't on one hand spend the first thousand miles at WOT banging off the rev limiter or on the other hand cruise around town lugging the motor at 1200 RPM you'll probably be alright.
2. The guy that writes the manual is not the guy that developed the engine. The manual guy is more concerned about minimizing warranty claims than maximizing performance.
I think in the end you end up making the choice between that last couple of percent of horsepower versus another few thousand miles before rebuild. But like everything I've said, that's just my guess. I never saw anybody come up with any hard data one way or the other. The differences people pointed at always seemed to be less than the natural variability between engines anyway.
What will I do when my car arrives? Well, there's the peeing-in-the-pants thing, but after that, I'll most likely do my best to follow the manual's instructions, but I won't feel bad at all about the times that tempation takes over. After all, if the guys unloading the car before I got it can drive it like hell, then I want to too.