Any experience with nIte ize steelie mounts?

Has anyone used nite ize steelie mounts? They look like a good solution for mounting devices in multiple vehicles and locations. I wonder if all of the kits can be interchanged though. I want to mount a samsung galaxy s3, however most of its time will be spent in a commercial vehicle. The magnets appear to be different sizes but the balls may be the same. I was thinking about using the larger magnet for tablets from the pedestal or hobnob kit mounted to the phone with the ball from the vehicle kit. I have had other mounts fail and when they do the phone doesn't just fall, it is sent flying around the cab. It's not about the vibration but about the shock from bobtailing or driving across rough terrain. If anyone has used them or know where they can be compared locally let me know. Thanks.

http://www.niteize.com/collection/steelie.asp