I recently purchased the CHOETECH Qi Wireless Charger Kit for Galaxy S5 Including Wireless Charging Pad and Wireless Charging Receiver on Amazon.
I spent quite a bit of time trying to find out if this charger would work in conjunction with an Otterbox case. I found very little to go by, but decided to take a chance. The answer is YES! My S5 factory back closed with no problems or discernible bulge. The Otterbox (Defender) fit just the way it had without the receiver installed. And, the charging pad works like a charm. At night, I remove my phone, still in the Otterbox clip, and set the whole thing on the charging pad.
I can't tell you for sure if there is much of a charging time difference. But I do know that my phone completes charging well before I get up. In fact, because I haven't disabled the audible charging alarm, I usually get awoken sometime in the night once the phone is charged and it begins a charge cycling on/off. I removed my phone from the charger, roll back over and go back to sleep.
The only problem I discovered was when I tried to use a dual port USB/Electrical plug. I had the charger and my Nook sharing the same adapter. Apparently, this was too much of a draw and was preventing the wireless charger from functioning. As soon as I placed them each on their own adapters, although still utilizing the same electrical outlet (both outlets, each on one), the problem went away.
I also purchased this company's car mount/wireless charger. The S5, in the Otterbox Defender bump case, fits securely and charges. The one detractor is that the charger causes static on the car stereo. Until I figure out the problem and a fix, I can't plug in the charger and listen to the car stereo at the same time.