I have and it just depends on what you are doing, I been using ikan for a while now and i like em a lot. The reality is that you will chose the right rig for you depending on a few factors including:
Accesories you are using
Lenght of shoot
and overall look of your project...
A Glidecam, can work very effectively but it had a rather long learning curve and need to be balanced each time you pretty much set your camera and with each different lens configuration...
In there other hand a shoulder rig, positions the camera like traditional broadcast camera. It allows you to carry multiple accessories on your shoulder(follow focus,Sound recorder, monitor, light etc.)Shoulder rigs usually are good for semi-long periods of time when you need to be on the move.(I usually run with the ikan Ofly (http://ikancorp.com/productdetail.php?id=630) a the Zacutto Z-finder and the ikan follow focus.