Hi dink,
I copied the fbneo.ini from the Sep. 22 version over to the new one and surprisingly it worked!
When I tried setting up the Sep. 22 version with completely fresh config settings, the aspect ratio was flawed again. It is a configuration issue or bug.
After deeply comparing all blitter settings, I found out that the old Sep. 22 version had in Select blitter -> "Basic", Blitter options -> "Scanlines 50%" activated, which logically should have no impact on the "DirectX9 Alt" blitter, but it does. Without this setting activated, the integer scaling with "DirectX9 Alt" blitter does not work.
Conclusion: With the newest build, setting up blitter -> "Basic", Blitter options -> "Scanlines 50%", then changing to "DirectX9 Alt" blitter and selecting Stretch -> "Correct aspect ratio", I get perfect integer scaling.
Please let me know if you would like to look at the fbneo.ini files to compare (or an excerpt of code).
Thank you for your time.