I've been changing my system over time and one thing I've noticed is that as graphics settings increase my ability to spot bogies just goes down. I mentioned this to the squaddies on HL lastnight and it seems others have noticed too.
I've seen previous posted pictures at differing resolutions showing how subtle but significant spotting dots becomes.
I've always tended to run the game at 1024 x 768 and set the game settings to my liking without crippling the frame rates. The new maps look fantastic but sadly dont help.
It would be great to see BoB use a better method of representing distanced planes but hey! what do I know.
Mind you a simpler technique would be to ban camoflage!! :/