I also can't understand, what problem you have with flashing the Phone with Emma? Whats exact is the problem? Are you afraid, that flashing with Emma, some "spy" stuff may come on your Xperia X? Well if so, you can't use any OS at all.. Are you know what exact is inside the binary blobs, even flashed under Linux and Fastboot? By the way, all Qualcomm Devices has this binary blobs, also FP2. So i see no problem here...