^^^ I've seen that too.
But personally, I think it looks much better on the back of the hood. Where did you hear that it made scratches?
I think it has a protective rubber encasing on the bottom of the magnetic device that connects it to the hood. So you should be safe.
Buuuut, if you have a shark fin, oh wait you have an e36. I have yet to see an e36 with a shark fin. But shark fins....work with Satelite radio as well.