Well, Terry, I'll give you my opinion (for what its worth), but I would also like to know how you feel about this sort of thing.
In those sports where instant replay is used for adjuducation its not instant. It takes from ten seconds to a couple of minutes to come up with a decision. Is this a good thing to have in the midst of sport sparring? I had always thought that one of the elements being tested in competition was a competitors fitness to compete, that is, their endurance. If, in something that can be as messy as sport martial arts, the competitors are stopping for an extended period for decisions (cause very few are at all clean) how is that endurance being tested? It will produce a different kind of competitor and possibly a different style of fighting.
I don't think that its a good idea. Double the number of judges, make sure that judges are not connected to the combatants, train professional judges, there are plenty of ways of avoiding contraversy without using instant replay (which still requires interpretation by a judge by the way).