We’ve tested both of these options and we consider the risk of failed prints unacceptable. The F306 is a very fast printer, capable of speeds of 250mm/s with good print quality. This requires uninterrupted data flow from the gcode file to the controller. Neither WiFi nor USB provide the guaranteed continuous high-speed data flow needed to keep up with the F306 with no interruptions, so we do not use it. The SD card in the controller provides directly addressable memory for the processor with no delay or interruption in the data flow.