I have experience with the company behind:
www.autokrassen.nl.
On the driversdoor a (+/-60 cm long) deep scratch has been filled with the same color of paint and has than been pollished. It can only be seen if you look at it from very close.
(Never fight about a parkingspot at Ikea on the 2nd day of easter. You will find your car back keyed by the insane woman.

)
On the right backdoor some scratches have disappeared after only being pollished.
(Never close the door by pushing it with a shoppingbag!

)
On the 5th door about 8 to 10 very short but deep scratches have been treated the same way as the one on the left frontdoor. These scratches can still be seen rather easily. Problem: the sunlight directly enlights the original metallic varnish and shows this way darker paint that has been used to cover up the scratches.
(Always carefully check if the 5th door can hit the ceiling of a car park!

)
My conclusion: repairing the varnish on the bonnet this way is a good way if you want to do it cheap, but in this case it 's not the best way.