The Navy did not use the Corsair because they thought it was inadequate for carrier ops. So they gave it to the Marines to use. The Marines used it to good advantage in ground support operations and air cover. And they showed the Navy it could be used on carrier ops.
Performance depends on model but believe the Hellcat could take a bit more punishment. This of course is subjective. They both were good planes and the Japanese respected both.
To exclude a plane because a plane that is already in the game performs nearly the same I think is a poor excuse. While I realize that it is more work on your end to code and draw the graphics, for us "historical minded" players that want to see a more historical head to head match up by period, I think it essential that the Corsair be included.
Marine Corps ace Pappy Boyington got the majority of his kills flying Corsairs with VMF-214, the "Black Sheep" squadron.