Probably a better indication can be found on the DLS itself.
Further searchihg on thr DLS found the following:
Buildings& Structures 61
Terrain Features 20
Textures Envvironmental 105
Textures non-environmal 0
Track 30
Track Accessories 11
Vehicles 3
Locomotives 0
Not much of a selection to build a complete layout from. So in all likelyhood most layouts built for TRS 2009 now on the DLS will contain objects not built for Trainz 2009 which may or may not run in native mode.
I have yet to see one made for North America. However all of mine on the DLS (except the one for TC1&2, have not tried it) work fine in compatability mode. Ignore any mention of missing content.