Hi,

 

I'm wondering the following:

• Is P3D V2.x scenery by definition compatible with P3D V3?
  (Regardless that it requires an updated installer)
• Or is the structure way different and needs V2.x always an update? (not installer)

Reason to ask:

Currently I'm in the process of installing P3D V3 and not all sceneries have V3 installers yet.

Can I just copy them, or should I wait for the officlal installer updates?

Short anwers: It might work, partially or fully.

The structure, with BGL's, DDS's and .BMP's is the same. However some scenery like OrbX use external dll's to "inject" features like animations and seasonal variations into the scenery outside of the SDK guidelines. They do this by accessing and mofidying specific memory locations within the Prepar3D process, and those locations change every time P3D is updated. This requires an update to dll's too.
However OrbX have partially moved to unified "*Flow" DLLs. In that case it's enough to have installed one v3 compatible product, and if the v2 product you're installing references the same unified dll's, it should work.