Loads of opinions on the net, but I went by the book. TBH, I suspect they are being cautious - the engines (I believe) are run in on the bench anyways? But the brakes, tyres etc, need a bit of time to bed in too (100 miles or so?) and expect other bits would like some gentle treatment from the outset.
I did a little light playing in the running in period, but its only after that I've bounced it of the rev limter - darn thing can't do 60 in 2nd! (last car did just!)
Paul