The Garmin mount system I have can also be turned 90 degrees. I have been thinking about mounting to bars instead of stem...view of it seems better from there. However, it is more comforting for it to be on stem
if in a crash situation or if bike were to fall over.

As the mounts seem to have had a lot of failures reported, I've seen some
Garmin Edge's (still using mount system) secured with velcro straps.