with my proposed changed for eldar holofield, most fleets will be a bit better against eldar, and the order of their competitiveness would not change.
i see ac being sent in to get a better look at the target, and make a hull straffling attack.
regarding proposed change for necron against torpedoes, it amuses me some that the strongest fleet torpedo wise might be orks (upward of a S6 salvo from an escort? whoa!) who might have been designed by the old ones to fight the necrons. The other fleet that would do well would be tau, who might have been modified by eldars. ha ha. btw, eldar would also do better against necron.
so while chaos might do better against eldar, they won't do much better against necrons.
while you can both change the saves for holofield and living hull saves, i think accross the board changes might be too much. more importantly, imo specific chinks/angles of weakness make a fleet more interesting to field, and to fight against.