Does the G3 require a replacement back to work with a Qi charger?
That depends on the model. The International (unlocked) version comes with the Qi back. The T-Mobile one needs either the new back cover, or the Quickview flip case with wireless charging. Then there is the AT&T version which uses a different wireless charging technology. All very messy actually. I had to spend $80 to get my quickcircle flip case with wireless charging.