I may be wrong but i doubt that it would make so much difference between just making a claim, and a claim resulting in a write-off. you have still made a claim non the less. Also i think that when you declare any claims they ask for more details so would be clear that it was accidental damage due to a defective bonnet catch rather thank bad driving. Sure, insurance companies look for any excuse to shaft you, but i think they have that in the fact that you are claiming in the first place.

I too would be happy to let them write the car off and end up with a couple of grand in the back pocket.