I have modified my hood with the flat neodymium magnets and it works very well!
To remove the hard drive magnets I used a method someone described on YouTube. The magnets are only attached to their steel backing by a bit of glue plus magnetism, by clamping one end of the backing in a vice I could bend the backing with a mole grip, which easily popped the glue bond so I could pull off the magnets. An alternative method is to use acetone (nail polish remover) to dissolve the glue. Not having any of that I used the bend the backing method. It only took about 5 minutes to remove 6 magnets.
I then found the best way to attach them to the hood was to use two magnets, with the hood tightly sandwiched between them, then to glue some soft material on the 'inside' magnet so it didn't scratch the paintwork. The hood is lightly padded and fully waterproof.
Being flat thin magnets they are strong but not too strong, the others I used were about twice as strong. It works very well and is now a doddle to attach and remove the hood in seconds.
I've never had any dents or damage using the older stronger magnets, apart from the one that managed to jump from my hand onto the door skin, it was a bugger to remove but only left tiny scratches which buffed out easily.