In my experience, engagement range is one of the most essential parts in missile point defense, anlong with AMM Speed, with some decent sensor tech, I tell you its possible to engage size 6 missiles at 8 million kilometers range using just 10 HS of active sensors, and that just pumps up the efficiency of your PD way way up. when you get maximum engine boost, if you design your missiles just right they should get speeds of 40k kilometers per sec, and with your agility tech, you should be able to get at least 30% hit chance on missiles going at 33k kilometers per second. with your reload speed, if you can research your way through this engine boost, and make sensors and fire ontrol capable of engaging at 6-7 million kilometers, if you put 20-30 launchers, you could very well engage in frequent combat, firing 1vs1 PD and not even get hit by a single missile most of the time, essentialy wasting all of their ordinance while recieving 0 damage (provided that you carry engough missiles to do that of course)