I did some experimentation in 10.50 this morning. KFDK was showing real world METAR with OVC013. I took off from KFDK and reached 2000 ft. without any decrease in visibility. The Cloud Area Covered in SMP was set to 10137 sq. km. I then decreased the Cloud Area Covered to 5192 sq. km and I was then in zero/zero visibility at 2380 ft. So far so good. This was with solid stratiform. However, when I climb above the stratus deck, the weather goes CAVU, i.e. I can see straight through to the ground. When I test this in 10.45, I correctly see a stratus deck underneath me.
Note that I double checked 10.45 and the SMP plugin shows ver 3.2.1.
Sparse particles works correctly as well even at 10137 sq. km, i.e. zero/zero visibility.
However, when I set it on dense particles, the weather goes CAVU.
As an instrument rated pilot practicing instrument approaches in x-plane, I'm trying to get the most realistic entry and exit into cloud decks.