I think the icon range at 6000 yards should say something generic like "4ENG", or "2ENG", or "1ENG".
Then at about 4000 yards have it switch to the model of the plane and leave it at that for good. I don't think 2 aircraft flying 350+ while doing a head on pass are going to be able to fully identify the exact variant of the enemy plane. Keep it as generic as possible. Spit, 109, P51, P38, 190, NiK2, A6M, Mossi, etc.
There isnt enough "fog of war" in AH, imo. 

I like the way he thinks. Now, I am gonna add some more fog to the discussion. My reasoning comes purely from my personal difficulty in visual acuity, but my view is not where most would think.
Krusty, I agree that we have a pretty solidly defined icon range in the main arena for the reasons that you have stated. However, I am not certain that Debrody's or the above opinion are purposefully aimed at tearing down the set structure. Keep in mind that as an individual with rapidly deteriorating eye sight, I agree that
icons are a very necessary equalizer for differences in monitor, graphics capabilities, video settings, or eye sight. In effect, no one can tell you what you see or should see, if they are not sitting behind your equipment and looking through your eyeballs.
Where I will probably stray from the conventional argument by someone generally in need of more icon help, is that
at some point in close it becomes more of a hindrance. At close distances, icons and even some gunsights become a
distraction rather than an aide. One possible solution for close proximity icons would be like Smokin' suggested above, less information. At this point, I am fairly certain whether or not it is a one engine plane and sometimes can even tell which variant, all that I really need to know is if it is a
friend or foe. (The distance counter might be something left on as an option in the training arena only).
One way to further such a discussion and bring in more data would be to give such options in the custom arena setups.

My wish