Used the EW-D at a gig last night. I ran an 18 inch cable from it to the Kemper. I thought everything sounded fine. There was no interference, but that place I played I typically don't get interference with anything.
The app did not work, at all. It said "Out of Bluetooth range or switched off". I tried making sure no Bluetooth devices were connected to my phone, turning Bluetooth off and on again, rebooting the phone, rebooting the EW-D. Nothing I did could get the phone to communicate with the EW-D. Good news is, with the front panel buttons, it took about 15 seconds to have autoscan run and have the transmitter paired.
Also broke a string during the middle of a song (Oddly, that is the first time I can remember breaking a string when playing in front of other people.) It has happened at home before, but never out.), and swapping guitars in the middle of the song took about 3 seconds, with the EW-D. I think it was a benefit of having an actual cable vs the G10S transmitter I would have had to put down.
I will try repairing everything, at home, to get the app working, but honestly since I'm only controlling one wireless unit, doing it from the front panel is fine with me.