Not sure why so much hate for mag mounts. Mine has never come off, gets excellent reception. It was only going to be temporary but now I see no reason to cut a hole in my roof.
I agree. They offer flexibility. I can move mine from the mirror mount to the roof if I need a larger ground plane to reach out farther...I could possibly even get it 20 feet up in a tree (since I still have the 25' of cable coiled up in a big loop in the headliner. Also if the antennae hits a solid object it will just fall off instead of getting sheared at the base.
They seem to stick pretty well also. The 5/8 wave has stayed on at 100 mph in the Scout, I had a mag mount CB antennae about 24" tall that came off of my cars roof at around 130mph...that will get your attention.
All that being said I like the cleaner install of a permanent mount.
Darrell