I had a "windscreen aerial" on a scirroco a gew years back, and wasnt really impressed with the quallity of it. It is a horizontally mounted aerial, and radio waves tend to be better suited to a vertical aerial, due to the polarity.
I mounted a new electric one on my wing last year, and to be fair, it wasnt really that difficult. Just remove a few screws from the plastic arch cover and it is accessable.