Re: break in - I agree it's like oil - lots of opinions. LOL, here's mine!
My experience having broken in various bikes since the late 1970's is to do what people have been saying. That is, don't lug it - don't wrap it out (go into high RPM's) if it "complains." And also - please do a lot of heating and cooling cycles, and avoid steady speeds.
I think you can kind of tell when the engine is broken in - it will be smoother and will burn less (should be basically zero) oil.
When I got my C5 recently, it was a 2012 with 1500 miles on it. I don't think it had ever been properly broken in. So I changed the oil, rode it conservatively for a bit - then changed the oil again and started doing some short bursts in the lower gears. I noticed that vibration started to decrease. I also rubber mounted the exhaust and moved the handlebar weights out a little father and mounted some bar ends.
I now have basically zero vibration and burn no oil. The bike will cruise at 70mph - and it won't "complain." I typically try to keep it around 62mph however (it's SUPER smooth at 62).
It took around 1500 miles for this to happen (I'm at around 3200 miles now).