Great thanks, I ended up making a UnoJoy adaptor as I didn't have the ProMicro, it uses the Arduino UNO with the bootloader flashed in DFU mode, and works well. I had a couple micro's arrive yesterday and got to work on yours also to compare.
Yours took a little more to get it to work and calibrated (more driver issues than anything... Win 10), but I managed it and it works quite well. If you attach the positive power from the receiver (+) to the high side of the fuse just above the USB port, you can do away with the extra USB plug that you are using to power the Rx, I have done it, and it works well so far. All you are doing is powering the proMicro and the RX off your PC USB port, nothing it can't handle if you don't try and power servos or anything. ;-)
Anyway, Just thought I'd share that with you, and thank you for your plans, it works very well. Great work.