Football has been coughing up blood and feeling tired all the time for years but I don't think a system where decisions can be made correctly when they would have been made wrongly can be a bad thing.
For years we've been lamenting how poor referees are, if things like this can help them then why not?
The why not could be if it's too disruptive to the flow of the game, but if the ball is in the net and offside was called then play has stopped anyway.