I've got a feeling that the USB charging port is the wek link in the entire construction of the rDNA. Wireless charging or switching out batteries is more convenient - well, at least for me.
I like the Vaporshark rDNA40 because it offers all three options - battery swap, fast USB, or wireless.
I tend to mainly use USB because I already have a USB cable at home, work, in the car, and in my travel bag. I need them for my phone anyway. No special chargers or spare batteries needed anywhere.
I've never had a USB problem in years of charging phones, though I am pretty gentle inserting or removing them. Of course, another good thing about VS is that if you do need it, they will replace the USB connector for $25 delivered.