I clayed the car today, after years of dismissing using a clay bar over fears of marring the paint.
Using the clay bar as directed didn't leave any scratches and left the paintwork mirror smooth. It took less time to polish the car afterwards with Autoglym Super Resin Polish than normal and left cloth much cleaner afterwards then polishing without prior claying.
I would recommend using a clay bar even after years of being sceptical. Have a look at some of the specialist online detailing suppliers as the clay kits are sometimes cheaper than Halfrauds even with p&p included, providing you already have some cloths to hand.
I'll take a photo of the clay bar later!