The PixRacer is a nice little piece of hardware, its not perfect but there is no evidence of a design flaw or incompatible components within this unit.
I fly the original and the Chinese knockoff with no difference. Have to admit that the metallic enclosure is a little unconventional and having the board moving within it is not a good feeling , so I stick the board with a piece of doubled sided foam tape on the bottom of it == make sure that you dont cover the baro. I put a foam tape under the ESP WIFI board as well so it does not touch the top of case , when plugged-in.
Maybe one important note here: I use Flysky PPM receiver that is conflicting with WIFI, for long distance I use the 900 Mhz SIK radio and remove the ESP8266 board, so I dont get erratic PPM signal.
The rest is just good construction technique, having a good vibration control, have a single source of power supply to the controller (no BEC from ESC connected) and never use USB except for downloading the new releases with the batteries disconnected.