Gas pressure is what presses the rings into the cylinder walls and get's them to seat. Taking it easy is an outdated and incorrect approach. It's also a great way to glaze the bores.
Assemble and run in with clean, dry cylinder bores. Use non-detergent 30wt for the first heat cycle (up to operating temp, vary revs). Shut it down, drain the oil, change the filter, drop the sump and look for metal in the sump and filter element. You'll always have some fine metal from your first run, but that's all you should expect to see.
Install new filter, and non-synthetic multi-grade oil. Allow to cool completely, adjust valves. Bring to operating temp, adjust mixture and timing, and go out and ride it fairly hard. Up hill, third gear roll-ons will give you the kind of cylinder pressures necessary for good ring seating. I have access to a dyno, and I break my engines in with full power pulls - and have never had a problem. If something was going to break under load, it wouldn't fare any better if I coddled it for a month first. Change the oil again after a half-hour of riding, inspect for evidence of wear or failure.
I'm fine with using Synthetic motorcycle oil after a 12-18 full pulls on the dyno or a few weeks of regular riding. Though many factory cars and bikes are run to their limits right off the assembly line with synthetic oil, I am still wary of breaking in an engine with it. I guess I cling to a couple of outdated beliefs myself.