It's not a question of security...the powerline speed depends on the quality of your electical system and the distance between the powerline units. It is good for short runs, but of course the signal must go all the way back to your electric panel so a short physical distance may mean a longer wire distance.
You would be FAR better with a hardwire connection. You ask if you should run one or two cables...and the answer is three cat 6 cables. One for computer to computer or for audio...and the other 2 for sending 1080p HDMI between rooms.
You would be FAR better with a hardwire connection. You ask if you should run one or two cables...and the answer is three cat 6 cables. One for computer to computer or for audio...and the other 2 for sending 1080p HDMI between rooms.