Part of the answer involves the height of the
repeater antennas above local terrain. Having
it a few thousand feet on a hilltop makes a
big difference compared to an antenna on a
10’ mast beside someone’s garage.
I’ve used mag mounts for decades, with various
types of antennas on them, and I keep coming
back to a 1/4 wave whip. If you also want 440,
get the kind with a small coil formed of the same
material as the whip, without any added joints.
Sure, the taller antennas may give you a bit more
range or signal strength at long distances over
flat terrain, but for local stuff the 1/4 wave whip
works well - I leave my mobile rig on the lowest
power setting most of the time.
Rather than worrying about a fold-over mount,
I just take off the mag mount when I go in a
parking structure where it bangs the ceiling.
But that isn’t a problem as often as with a
longer antenna. If you are only using it
occasionally, just leave it inside your car
until you need it.