Is that true? I heard for the X3 the pogo pin cable they ship has 2 pins not 4 but you can buy one and it will transfer data and let you flash custom firmware.

I own both an "old" X4 as well as a "new"/"domestic"/locked X3. The pogo cable transfers data, and the device shows up in dmesg when connected, but disappears shortly after. The cable itself works fine for transferring data, tested with a different device with the same connector.