Something interesting I noticed was that when I plug in the fast charger into the wireless charging pad, the indicator light is a lighter blue compared to the darker blue of the cable it comes with. Does it have some sort of effect on the charging speed? I don't know why it would have three different lights.
I have a hard plastic case on my Lg optimus g pro and it works fine with my china made qi charger pad ($6.00 for the pad) using it over a year now, and works great.
I have a small portable Samsung charging pad that came as a kit with the back cover replacement for the S5, and it works well. The pads top surface is almost like faux leather, and I'm hoping that it will supply sufficient grip for use with the S6.
In order to tell at a glance whether your phone is charging the Wireless Charging Pad does have a nice little LED array on the front edge of the charger that will light up a light blue when charging and green when completely charged. During the day the LEDs aren't quite bright enough to be seen from afar, but at night they may be bright enough to bother you if the charger was next to your bed. We didn't have too much of a problem with it, but wouldn't be surprised if the always-on light while charging was a deal breaker for those who wanted to charge overnight with it.
Samsung PMA-7 Wireless Charging Pad (Version 2)