The thing that forced me to write is the Su-25 HUD I saw in screenshots. It's not even close to the real one.
First of all, the main mode of Su-25's targeting optics (ASP-17) is automatic mode.
In auto mode the element you use is the moving round-shaped mark with crosshairs in it.
It's position depends on aircraft's position and movement parameters. Meybe it's difficult to model... Than we have a static crosshairs.
Both, static crosshairs and the moving mark, can be seen simultaneously but they have separate brightness controls which allow to fade one or another.
The same thing is for hte Ka-52 HUD. It has soviet/russian indication system!
I think many players would be glad to see _real_ targeting marks in the HUD of russian aircraft.