Why still no dive acceleration difference?

[JtD]

mayshine, I've recommended you to do this test:

Take a Fw 190A-9 and a Spitfire IX 25lb, start at 550 km/h at 1.5km altitude and dive them to a place 15 km away. Check their speeds.

Have you done it?

I can also assure you that the issue has been brought up again and again over the years and that il-2 is fairly accurate at typical combat speeds. The limitations will be reached only when you reach very high speeds, where the effects of near sonic flight are not as strong as they are in real life.