I hope that no one flames me for resurrecting a thread like this, but I was thinking along the same lines as introducing some form of smaller ASW escort, and the escort carrier to use in the A&A Pacific and A&A Europe game. The British had a range of ASW ships, from the small Flower-class corvette to the much larger escort sloops and Lend-Lease destroyer escorts. The destroyer escort was intended specifically as an ASW ship, and was actually more capable at ASW than the normal destroyer, having as good a sonar suite, and the ability to deliver a much larger depth charge pattern, along with Hedgehog attacks from 1943 on. It was generally viewed as being about 1/2 the cost of a destroyer, which would give it a cost of 6 IPC, an attack of 2 against surface ships, defends at 2 verses ships and planes, and attacks and defends against submarines at 3. You could drop the attack and defense rating against planes and surface ships if you really wanted a bigger difference than the destroyer.
The escort carriers were pretty much either converted merchant ships or built according to merchant ship standards to modified merchant ship designs. That would give them an IPC cost of 8, not counting planes. The British used some escort carriers as fighter carriers for amphibious landing coverage, and those could be viewed as carrying two fighters. You could restrict those to defending against air attack and maybe having a 1 for ship attack. Otherwise, the normal air group was 12 to 19 Wildcat fighters, and 9 to 12 Avenger torpedo planes if American, or Swordfish if British. This would carry only one fighter, but it would have the regular aircraft stats for attack and defense as representing a mixed air group. If you wanted to, you could use some of the 1/700 scale Avengers or Swordfish and give it a special ASW capability with limited air combat ability. If you did that, you might want to boost the cost of the aircraft up two IPC over a straight fighter.
For units to represent these two types, I was thinking about using the destroyers and carriers from my Attack Expansion game, and designating which color went with each country. Then I do not have to keep track of cardboard counters.