Best answer is that some have and some haven't, it's a personal choice. I changed the oil in my MCS just after the break in period and then I change it every 6,000 miles.Has anyone bothered having the oil changed after those first thousand miles of running in? Its not recommended officially anywhere I can see, but I'm tempted to have it done, or am I just throwing money away which could be spent on cleaning it!
When I test drove my first JCW I really wrung it out and everyone that I run with did the same thing. When I bought my R56 JCW it had been on the showroom floor and test driven several hundred miles before I bought it. I kept it for 4 years, drove it hard from day one and never had a problem. When I ordered the F56 JCW I didn't baby it either although I did not maintain high RPM's for any length of time. I have put 12,000 miles on it since November of 2015 and the engine has been flawless. I did have the oil changed after 2,000 miles as I wanted to see the oil, smell it, and rub it between my fingers. It was fine.Just drive it how it's meant to be driven, modern engines are bench tested and don't need running in.
Considering at least 9 out 10 new cars are either rentals, company or even dealer demos and not one is run in but driven hard from day one, if there was a issue with this there would be a lot of cars waiting for new engines!
When I brought my R55 JCW I had a 40 mile drive home, motorway, country lanes etc and boy that was a great ride home, owned for 4.5 years and not a drop of oil used or issues and this was from the N14 engine.
They need to be driven not held back...