Ive had 3 and they all fell off my cars-
And regardless of what many may think- i dont speed
The radioshack antenna (for me atleast)will stay on the car
IF you mount it to the trunk, but for some of us with aluminum parts, the trunk isnt an option. or for many of us with SUV's, theres no trunk available. So i mounted mine to the top of my 2 vehicles(a Chevy Avalnche and Nissan Altima). Each one fell off at around 50-55mph. Scratched the hell out of my Altima. Same with the first one i ever got for my 81 honda accord(way back).
I keep coming back to the RS antenna because to me, its the best one ive ever used as far as "hearing" things. I also own/use a Larsen mag mount-its just not as good-IMO
To combat my bad luck with the RS antenna, I did this.---->
http://forums.radioreference.com/pictures-your-shack-mobile-setup/104499-bct15-gps-temp-install.html
I dont have the car anymore, but i definately have the antenna. I already had the parts lying around for this. I thought i might share with you my idea since you mentioned getting the LiL Wilson(mine was/is a Wilson1000 mag mount).
---my $.02